Text Layer Upscaling Proportionate Kerning

Starting with 400x400 image size, with 40 pt text layer. 2 letters, kerned at 5.

Wanting to create the same text layer with the same kerning at various larger sizes. For example: 500x500 image size with 50 pt text layer, 1500x1500 image size with 150 pt text layer etc.

Simply typing the larger text layer in the larger image size can produce different kerning positions. Normally one px difference.

To confirm what the new size should be regarding the correct kerning, I have tried every way of testing I can find using upscaling techniques and they can all give different results. It also changes depending on what size I use to upscale with.

• Increasing image size
• Increasing image size with Scale Styles 
• Duplicating the layer, sending it to the new canvas and increasing the font pt
• Converting to smart object, opening text layer as .psb and then increasing font pt
• Free transform as a shape and smart object
• Free transform as live text (this can produce kerning differences within dead zones)

If I can’t type the new text layer and trust that kerning placement and I can’t upscale a font pt and trust that kerning placement, how does one determine the correct kerning at different sizes?