I've done the aero and gear calculations. 69 fastback, coefficient of friction of 0.65, pretty crappy, so the top speed isn't all THAT high, with 500 horsies at the fw. With the power, I should be able to get 165mph, using a 5.0L DOHC modular motor with billet rods, and forged crank and pistons, and some slippery coatings on certain bits. I've been told by the engine builder that it will go "9000+ rpms". I was planning on a TKO II, hopefully a TKO, with the better overdrive. I won't build it to rev that high, I'll use a very streetable cam, so max power probably 6500 or a little higher, limited to 7500 or something. My goal is a car that sounds like an insane asylum at WOT. Anyways, I think cruising is more important than gearing to max speed, and it seems smarter to reach top speed in 4th, not OD, for strength reasons. It just seemed a bit silly to have a potential (max rpm) speed of like 350km/h or more, when the car won't actually go that fast due to wind resistance.