Need someone to check my print sizing

Well, not much to add to what Trevor says. If this is the full original size, it won't be optimal - not because it's a large print, but because it's really a small file for any print size. A magazine spread would already be a bit too much for this.

Not that it isn't possible. Any file can be printed at any size. The question is how it will look.

I'm not worried about visible pixels here. 100 ppi should be passable in that regard - that's roughly what you have on any standard computer monitor. You don't see pixels there. But you won't be able to get the snap of a tack sharp image. It will be a little mushy.

You might run this through the neural "remove jpeg artifacts" filter, and then perhaps super zoom, but I'm not sure it will do any good.

One thing - the grayscale profile was thrown out by Photoshop, not accepted, so it's probably a very non-standard profile variety that you really shouldn't use. I had to assign one, and Gray Gamma 2.2 looks pretty good. I'd assign that.