Big Block help needed

[c502]

Hi all. I've read about every post I can find on doing a BBC swap in my 71 K5. I have this pretty Ram Jet 502 in my garage, a custom rebuilt Turbo 400, and a fresh NP 205 ready to drop in, except it won't just drop! 2" body lift and I'd really prefer to not hammer on the firewall because I'd have to hammer a lot. Also, the stock crossmenber and the oil pan are hitting in multiple places using the small block mounts..

I have tried the following:
1) Placing it on the stock small block mounts. See above.
2) Buying Big block 2wd towers. Obviously that wont work.
3) Pulling a motor out of one of my many 73-87's to get the crossmember out of it. I would have no problem drilling the frame and moving it forward but the actual mount (the parts that bolts to the engine and the crossmember on each side) is at least 1/2" too large to fit between the 71 frame rails.

I don't mind spending the money to find something that works but I need some advice which way to go. Any advice would be appreciated.