I would say the question is what do you want to do with it?
-3.0l with 3.0l 2001+ heads
I'd say this is the best current solution with the ST200 cams and some minor head work for the best gains cheaply. It also leaves the door open for a Turbo or Supercharger later.
-same as above with hc pistons
Best choice for the N/A croud as they get the advantage of the Higher Compression and the larger Valves.
-3.0l with 2.5l heads
Most widely in use but does suffer some from the smaller valves in the 2.5 heads. Gets good gains from the Higher Compression though.
If you have the Lower from the ST200 a set of adapter plates can be made for the 2001 heads to have it bolt up. Jiako's Machinist has said he would sell them if there was interest.
