I purchased a wrecked 2wd 1980 Toyota with 90k miles and running for $400 to drop into my '87 after the timing chain jumped and screwed my motor.

Will a 20r from a w50 bolt up to a g52?

 

Check out marlin crawlers transmission page, they have bellhousing patterns listed, i Think.
i believe it will bolt up.
The other thing to remember is 20rs have slightly different carb, intakes, ignition and i think exhaust port shapes.

 

How many miles were on that '87 engine when the chain jumped?

 

Have you pulled the head on your 1987? It's possible the damage is limited to bent valves or damaged head.

 

I had to replace the head on my 4-Runner. I lent it to a "friend". While he was driving, it threw the water pump belt. Did he replace it with the spare and tools I keep in the truck? Naaahhh. He drove it till it overheated, let it cool down, drove it till it over heated, etc, until he got it to my house again. Cracked the head pretty good.
I got a new one, and IT was cracked.
After two heads, and, of course, gasket sets, I finally got it running again. Never again lent my truck out!

Replacing the head isn't all that hard, really.
Pat☺

 

I've done my research on the differences from a 20r and 22r.

My 22r was around 260kish on a "rebuild" and my valves are bent, but the pistons are all chipped, and it looks like they've been rattling around in there

 

Well it should be a fairly easy swap if you can get all the accesories.

From my understanding, the 20r block can also be bored out to 22r spec.
Ive got a 20r in my 1980 yota and absolutely love it. 22r has slightly more torque but a fresh 20r will get the job done no question. Are you going to work on it or install it as is?

 

My plan is to do preventative maintenance (seals, oil change, tune, etc) and throw on a new weber since the previous one was parted out. I'll also do a clutch/flywheel for good measure since mine was starting to fail before the timing jumped. After I get the 20r up and running, I'll get started on sourcing parts for a "fresh" 22r to throw back in