for the 3.0L... some extremely speculative info...
I have been thinking a lot lately... and doing some researching...
The stock from the factory 6g72 12v SOHC engine puts out a whopping 142hp at the crank...
The 10:1 mitsu version puts out 164 hp... so that leads me to believe that 10:1 pistons are worth about 20hp (same engine, same year, only diff is pistons... both are 12v)
The montero came with 24v heads... i'm not entirely sure how the water jackets are set up... but the montero put out 177 hp (if someone knows, please pm me) thats 35 hp over the 12v... oh, and thats with 9:1 compression, vs. the 8.89:1 compression of the chrysler version...
the new eclipse 3.0L 24v puts out 205 hp with 9:1 compression...
again, this is all speculative... but i would estimate 200 hp with just heads (if they fit) and 10:1 pistons... this is all n/a... then add all the above stuff, i'm seeing 225 hp from bolt-ons, heads, and high comp pistons... thats comparable to the dohc n/a...
still not enough? open up those heads and do a few more minor modifications... i figure around 240 hp n/a... if not more... fabricate a set of headers, you're sitting at 255 hp or so...
STILL not enough? yank those high comp. pistons, slap in some 8.0:1 comp pistons, replace those headers with a turbo manifold, and i could easily see 325 hp... comparable with the dohc-tt... and a similar setup, actually...
again... this is all speculative...
and i did a little bit of looking (head gasket comparing) and it looks like the water jackets between the 12v and 24v sohc are slightly different, but not majorly... i think the bigger hurdle would be having them mount up and run the belt correctly... with all this stuff, you now have an interference engine...
i plan on going tomorrow to see if the local u-pull-it has any 24v montero heads
if nothing else, i can clean them up and sell them on ebay or something...