It looks like ISO, but I'm not sure. My buddy gave me a sparkling peugeot frame with a bottom bracket, fork and headset so I guess I'll be making a conversion. Can you guys recommend me a cheapo crankset to throw on to this taper? The axle length looks to be 111mm or 111.5mm.

This'll help:

https://sheldonbrown.com/bbtaper.html

Comparing it to the info on Sheldonbrown, it looks like its J.I.S Low Profile, just by how the flat part creates kind of an ellipse shape from the bottom to the top.

Upon closer inspection it looks to be J.I.S Low Profile. Does that mean I have to find cranks with that taper or can I just throw a normal J.I.S tapered crank on there? Perfect chainline isn't really a necessity for me.

Probably go with the low profile just to be sure, I'm not all that sure about tapers and cranks, but best fit with what goes best with the taper

Do you know where to look for a relatively cheap option? I'm gonna head down to the co-ops, but low profile seems like something harder to find.

You can replace a BB for less than $20. Why go to all sorts of effort to find a crank to match a BB?

Because I'd prefer to stay in the $100 range with this build. If I find a cheap crank with a cheap matching bb I will pick it up of course.

Last crank I can remember using the low profile JIS was Dura Ace. Have fun keeping that under $100.

Fair enough, but I've yet to get an answer as to whether throwing a normal jis crank on there would be an issue.

There's no way to know whether the junk you pull out of the bin will work with it. Chances are good that it will end up farther inboard than otherwise, you'll have to experiment and see if there's still enough clearance to the frame.

Yep, it's definitely square.

I have no clue what that thing in the foreground is, but I'm pretty sure thats the base of one of these:

I think this thread has run it's course, but just to please you: