You will want to consider the new weight distribution problem that comes along with this engine swap. The stock Pantera has 38% front weight distribution and 62% rear weight. With the big block, unless it's all aluminum, will increase the rear weight, and thus go even further away from the optimum 50%/50% front/rear weight distribution. Maybe it 42%/58%, I forgot, but is +/- 2% from 40%/60%.
So, this means handling issues to sort out. More understeer in the corners. Heavier spring rates in the back isn't difficult to correct, but the steering problem will persist.
I'm gathering info to add a Paxton supercharger to my 351-C for the horsepower project.
Maybe I can persuade you to help me gather info and try and plan out details ahead of project initiation. I want to sort out as many issues ahead of time as possible, to reduce Pantera downtime (or reduce Pantera 'up-time', up on jack stands and out-of-service).
Please see p/n 769-1001839 at
www.jegs.com or for the polished version, the p/n is 769-1001839-P. This is a product that is designed for a bolt-on application for the 1964 - 1968 Mustang 289/302ci w/Carburetor and includes the NOVI 1200 supercharger.
When pumping more air in through the carb, like with superchargers or turbochargers, you want a lower compression engine, or it'll blow out intake gaskets and head gaskets. There's a NOVI 2000 supercharger that pumps even more air flow into the carb, for more horsies, but I want to keep the engine from blowing up, so the NOVI 1200 looks a little less than maximum capacity. It's supposed to add 50% to 60% more horsepower, so for $2,599.99, unpolished, even with custom brackets to repalce the A/C bracket (have to delete the A/C compressor) and some custom fabricated intake plumbing from the supercharger, around the header to the carb, seems like the 'best bang for the buck' to me.
This also enables one to 'revert' the process back to 'stock' if that ever became a desirable goal. It also keeps the handling 'as-is' and allows use of the stock engine screen behind the rear window.
'Louis LeEyeball' engineering estimates are about $3,500 for 450 to 500 hp, without any significant weight increase.