I assume your 4V heads are open chambers?
You can keep them but you need special pistons to obtain a sufficiently high compression ratio. You should also know that it is more expensive to have them modified to fit roller rocker arms, bronze valve guides, stainless steel valves with good springs, than to buy ready-made aluminum cylinder heads.
You haven't told us if you want to build your engine yourself or have it done by a professional? If you want to build it yourself, you should know that there are a lot of parts to choose and buy in the US and it takes a long time.
Do you have read the threads of Georges on the forum, it's a very precious mine of informations:
https://pantera.infopop.cc/top...d-performance-tuning
https://pantera.infopop.cc/top...mber-4v-heads-q-code
Here is the configuration of the engine I am building myself:
- original block 4 bolts reamed to 4.020 "
- forged Scat crankshaft 3.75 stroke (383 CI)
- 6.25 " Scat I forged connecting rods
- Rosspiston custom forged pistons
- Original heads with ports slightly ported by me and bronze guides
- Special Bullet camshaft according to Georges specifications
- hydraulic roller lifters
- Compcams roller rockers
- Ferrea and Manley stainless steel valves
- Holley 750 cfm #9379 annular boost
- Blue Thunser intake manifold
- europa GTS headers
It is also necessary to install liners in the tappet bores to improve the lubrication of the engine (Wydendorf Machine)
The block and cylinder heads are currently with my machinist for the reaming and installation of bronze valve guides and the modification of the pedestals.
I have a transmission with the original ratio of 4.22 / 1