This whole thing would make more sense if the words "Cost too much to rebuild" wouldn't just be a flag waiving at full staff on Idontknowwhatimtalkinabout Island.
On what planet do you currently reside on? Just because your friend threw together a combo that turned out to run poorly, doesn't automatically mean every freakin 5.0 will run that way. Mof 99% of those who participate here can vouch for that. A mild 302/5.0 will be every bit as responsive, fits the K member thats in the car, you can reuse the power accessories, and will flat out bitch slap a 2v 4.6 in any contest you put it in.
What kind of black hole do you spose you're gonna find when it comes time to fit the 4.6, to fuel one, to get past the PATS, to get it running?
Versus the relative "bolt in status" that the current drive train enjoys, buy yourself a decent rebuild combo for the existing engine, put a new carb on it and go. Swap in a t 5, upgrade the brakes and rear with the donor, and put the rest of it on CL.
* By the way, I don't just play a know it all on web forums, I am one in real life.
4.6 2v in a fox. Ported p.i. heads, stage 1 cams, Edelbrock induction, MSD timing computer. Tr3650 trans, 8.8 rear.
Manual brakes, Manual rack.
A Genuine pain in the dick to drive, and an even bigger one to stop.