Ok, it's a long story but here goes:
I recently bought an IS300 for practically nothing from a broke "mechanic" that bought it from his roommate to fix and drive. In our initial conversations he explained (for some reason) they swapped the head on the original 229k mile motor. After swapping the "low milage" head onto the block it wouldn't start up. The mechanic said it's because he didn't shim/adjust the valves properly so that's why it wouldn't start.
Keep in mind I only bought it because I just assumed whatever hackjob backyard job he had done wasn't worth the time to try to diagnose what exactly wouldn't allow it to start when I could just purchase a used lower milage motor and just swap it in, which is something that is worth my time. When I went to go take a look at it, it looked like he really didn't do too bad of a job on putting it all back together, so MAYBE it really just is the valve/cam adjusting that is keeping it to fire. I don't know enough about the motor internally to diagnose this myself, nor do I have the time to trouble shoot. My thought, is if I can save a couple hundred bucks and someone can get it running there is no need for a motor. Is this making sense?