The parts are out there. Look mainly for stuff involving the rocketblock and superduty, I think. For the most part your are going to get the same responce, which is swap. If your buddy wants to be hard core though, he can build a killer Duke. Just make sure he's prepaired to shell out abuot 25k for it.
The problem with the duke is that the stock parts were built to be light weight and once you start increasing HP and TQ, those parts are going to start needing to be replaced. Mainly the rotating assembly. That's why most of the fiero guys, myself included, are swaping the 2.5 for quad 4's and other things.
Right off he can look for the following parts for it:
Holley Big Bore
Holley Big Bore intake(good luck!)
1.7 BB rockers(may need to have studs put in)
That is about it for bolt on's and minor engine work. Next would be extensive. Plus the above would run him $1400, estimated.
Hope that helps.
'91 Z-28 5.7, SLP 1 3/4 headers, 4 inch Mufflex/Flowmaster cat back, gutted cats, Edelbrock intake, 8.5mm Jacob wires, MSD Blaster coil, S&W subframe setup, Jacob Pro Street Ignition, Harwood glass hood, Spohn lower control arms, complete Kenwood system, and a few hidden goodies.
IDP.........bring'n it back once again!
Forced Induction 427?..........................on HOLD!!!
Stealth Ram......In polishing phase
Soon to be World Castings 427 sbc
SLP 25lb injectors