Need help fixing an outdated script in Illustrator

Changing line 63 corrects the y origin for CS6+. However, it breaks the function which draws the borders. This is dependent on the condition that width is < "lastRow", which is 30. I don't know what this means. Disabling the condition (line 39) gets the script working, but I can't guarantee that it hasn't broken something else.

var lastRow = 30;
if (documents.length > 0) {
    var sourceDoc = activeDocument;
    var artLayer = sourceDoc.layers[0];
    if (sourceDoc.pageItems.length > 0) {
        sortWidths();
    } else {
        alert("Please add at least 1 image");
    }
} else {
    var sourceDoc = app.documents.add(DocumentColorSpace.RGB, 864, 1296);
    var artLayer = sourceDoc.layers[0];
    if (sourceDoc.pageItems.length > 0) {
        sortWidths();
    } else {
        alert("Please add at least 1 image");
    }
}
function drawBorder(widthsArr, rowHeight, rowPos) {
    var max = sourceDoc.pageItems.length;
    for (var i = 0; i < max; i++) {
        // get the boundaries, then add .35" to them and create a rectangle
        var gbounds = sourceDoc.pageItems[i].visibleBounds;
        k = widthsArr[i];
        var hTop = rowPos[k];
        var hLeft = gbounds[0];
        var hWidth = gbounds[2] - gbounds[0];
        var hHeight = rowHeight[k];
        var vTop = hTop + 18;
        var vLeft = hLeft - 18;
        var vWidth = hWidth + 36;
        var vHeight = hHeight;  // + 36;
        if (vHeight < 144) {
            vHeight = 144;
        }
        if(vWidth < 72) {
            vWidth = 72;
        }
        // if (k <= lastRow) {
            var rect = artLayer.pathItems.rectangle(vTop, vLeft, vWidth, vHeight);
            //fill is none, send to back
            rect.filled = false;
            rect.zOrder(ZOrderMethod.SENDTOBACK)
        // }
    }
}
function sortWidths() {
    var widthsArr = new Array()
    var max = sourceDoc.pageItems.length;
    for (var i = 0; i < max; i++) {
        widthsArr.push(sourceDoc.pageItems[i].width)
    }
    arrange(widthsArr)
}
function arrange(widthsArr) {
    var done = 0;
    var adjustHeight;
    var rowWidth = new Array(1);
    rowWidth[0] = 36;
    var rowHeight = new Array(1);
    var rowPos = new Array(1);
    rowHeight[0] = 0;
    rowPos[0] = - 36;
    var arrLen = widthsArr.length;
    while (done < arrLen) {
        var max = 0 ;
        var biggest;
        for (var i = 0; i < arrLen; i++) {
            if (widthsArr[i] > max) {
                biggest = i;
                max = widthsArr[i];
            }
        }
        done++;
        widthsArr[biggest] = 0;
        var gbounds = sourceDoc.pageItems[biggest].visibleBounds;
        var hHeight = gbounds[1] - gbounds[3];
        var vHeight = hHeight + 36;
        var hLeft = gbounds[0];
        var hWidth = gbounds[2] - gbounds[0];
        var hTop = gbounds[1];
        var vTop = hTop + 18;
        var vLeft = hLeft - 18;
        var vWidth = hWidth + 36;
        var vHeight = hHeight + 36;
        var width = vWidth;
        var height = vHeight;
        if (width < 72) {
            width = 72;
        }
        if (height < 144) {
            height = 144;
        }
        var numRows = rowWidth.length;
        var newRow = numRows - 1;
        for (var i = 0; i < numRows; i++) {
            if ((rowWidth[i] + width) < sourceDoc.width) {
                sourceDoc.pageItems[biggest].left = rowWidth[i];
                widthsArr[biggest] = i;
                rowWidth[i] = width + rowWidth[i] ;
                if (rowHeight[i] < height && rowHeight[i] != 0 && (adjustHeight > i || adjustHeight == undefined)) {
                    rowHeight[i] = height
                    adjustHeight = i;
                } else if (rowHeight[i]<height) {
                    rowHeight[i] = height
                }
                sourceDoc.pageItems[biggest].top = rowPos[i] - (rowHeight[i]/2 - vHeight/2)
                i=numRows + 1;
            } else if (i == newRow) {
                widthsArr[biggest] = i + 1;
                rowWidth.push(width + 36);
                sourceDoc.pageItems[biggest].left = 36;
                rowPos.push(rowPos[i] - rowHeight[i]);
                rowHeight.push(height);
                var k = i + 1;
                sourceDoc.pageItems[biggest].top = rowPos[k];
                if ((sourceDoc.pageItems[biggest].top - rowHeight[k] - 36) < 0 && lastRow > i) {
                    lastRow = i;
                }
            }
        }
    }
    if (adjustHeight !=undefined) {
        adjustH(adjustHeight, widthsArr, numRows, rowHeight, rowPos);
    } else {
        drawBorder(widthsArr, rowHeight, rowPos)
    }
}
function adjustH(start, list, rows, rowHeight, rowPos) {
    for (var i = start; i < rows; i++) {
        if (i != 0) {
            var k = i - 1;
            rowPos[i] = rowPos[k] - rowHeight[k];
        }
        var listLen=list.length;
        for (var j = 0; j < listLen; j++) {
            if (list[j] == i) {
                var gbounds = sourceDoc.pageItems[j].visibleBounds;
                var hHeight = gbounds[1] - gbounds[3];
                var vHeight = hHeight + 36;
                sourceDoc.pageItems[j].top = rowPos[i] - (rowHeight[i]/2 - vHeight/2)
                var max = sourceDoc.pageItems[j].top - rowHeight[i] - 36;
                if ((sourceDoc.pageItems[j].top - rowHeight[i] - 36) < 0 && lastRow > i) {
                    lastRow = i;
                }
            }
        }
    }
    drawBorder(list, rowHeight, rowPos)
}
function sortNumber(a, b) {
    return b-a
}