One thing to consider when swapping to a bigger engine is the drive train. The stock 2.6 drive train probably wouldn't be up to the power from the 3.5L v6 much less a v8. Its why mitsu went to a beefier rear end in the v6 and TD models. If it were me, I'd throw the big locking rear end from a gen II SR under there. If you haven't seen it... trust me it's substantial and you get a locking diff to boot. The gearing options for that rear diff are either 4.2 (gen 2.5 version), 4.6 (gen 2 version) or you can put 4.9 (01-04? sports). Not sure what solid axle you're looking at but it would need to have a matching gear option.

Also, If power's really what you're after I know someone with a turbo 2.6 thats pushing enough boost that he blows away corvette's on the open highway going uphill <img src="/forums/images/graemlins/zombie.gif" alt="" /> <img src="/forums/images/graemlins/zombie.gif" alt="" />. That's Jason who's occasionally on this forum. Currently he's sourcing an auto tranny cause his manual tranny cannot handle the amount of power coming from his engine.

Also what kind of timeline are you thinking this project will take? Weeks? Months? Years?

As for the other engine's you're asking about, can't say. Nobody I know has tried putting them in so you'd be on virgin territory with them.