Compared to you, Pittsburghracer, I am a good gen 3 racemotor candidate. I have NO spare parts for my 528, but i do have mechanical fuel injection that only requires a mounting bracket for the pump and a manifold, and have acquired Apache heads complete ready to run, a 3.888 crank, early 5.7 core motor, good rods, SRT exhaust and complete intake system plus a Helcat blower assembly in need of a front bearing.
It would be cheaper to build a 380 inch gen 3, and with the heads flowing 340 cfm right out of the box I would think 750 hp would be a piece of cake. Better yet sell the crank and rods and go as big as the 5.7 will allow, have the heads touched up a bit and be within a tenth or two of my current motors performance for a LOT less than I have in that piece.
In the end, it really is more about what we like. With your stash, a garage sale would get you enough cash to fund the project from what it sounds like. The fact that you posted this says you might,, some day.