A500/42RH is the overdrive version of the A904, right? A really good fit for our cars, as long as the engine doesn't put out too much power. Used A500s are in the $500 range up here.
Bullet Bob, do you know if the Magnum A/C compressor and power steering pump would work with the original air conditioner cores and power steering boxes in the F, M, and J body cars? I would think that there may be issues with the A/C compressor, as it is probably made to use R134a vs. the factory compressor using R12. if you use the Magnum compressor, can it be controlled by the factory air conditioner controls in the F,M, and J bodies?
Ollywood, you can address the weight imbalances somewhat by moving the battery to the passenger side of the trunk with a battery relocation kit. Putting the battery on the passenger side will help balance the weight right to left, and also help some with front to rear. If you want to take more weight off the nose, look at aluminum Magnum heads and intake manifold.That should take at least 100 lbs off the nose, probably closer to 150 lbs for heads, intake manifold, and battery relocation. If the battery is relocated, you will be adding 40-60bls to the rear, which also helps front-tear balance.
Kostas