Here is what I found on my car.

1. The factory Magnum manifolds will not clear the power steering box. They do but are about 1/8" off of it, so the box would suffer heat problems.
2. Magnum Headers will not clear the steering column so I am going with LA engine headers.
3. The factory Motor mounts for a 74 and older car will work fine.
4. You will need a LA 360 oil pan and pickup for you car. Not hard to get.
5. The Magnum's are a different balance so make sure you use the correct flywheel/flexplate & Torque converter.
6. The van power steering pumps use a different mount and you will need it to clear the battery.
7. If you use an A-518 OD tranny you need to replace the cooler lines with 3/8" lines. The 74 and older lines were 5/16" and are too small.

I hope that helps you some. I will post Wiring diagrams tonight when I get home from work.

Sorry for the Hijacked thread.