Ask Marlin about the plate; am thinking it should work.

DO A COMPRESSION TEST and a leakdown on the donor truck so you have a point of reference; if it's running, but the numbers are on their way out, then go ahead and rebuild the darn thing. 142-171 psi, +/- 4%. If numbers adjacent to each other are low, you might be looking at a head gasket.

Also, before pulling the engine, flush it out and put some descaler in there; open up the heater core, and give it all a good flush. No sense in putting it all back together if it's still gunked up in the plumbing; make sense?

You might need to do a little floor pan work to compensate for the shifters (side v. top). Check our Toyota FAQ here above for more specs. '80 I believe was the only year the Yota got that L43, so I think you'll be okay xmember wise, but do the reading. Bellhousing should bolt right up.

That's all off the top of my noggin enyhoo.