You already have the 429 in the car, right? So, why throw obsolete motor mounts into the equasion? The exhaust can be manufactured by just about any muffler shop, so don't use that for an excuse.
If it was mine, I'd yank that 429, have it rebuilt to my specifications and throw it back in that bad boy. Nothing like originality IMO. My wife is 55 years old, and gets a big smile on her face everytime she drives her Mach 1. Don't sell the women short. At any rate, the 351 Windsor can be modded, but certainly nothing like that big block 429.