Hey Al,
with the 4.56 gears you don't really need a lot of motor to get up and around and over stuff... You just need a motor that doesn't stall out on inclines and something that runs good at all RPM's. That having been said, if you want to build a 'stroker' motor, you'll need to find a 4.0 block and then get a 4.2 internals, like mainly the crank and rods then put that together with the 4.0 pistons (the bore is different on these two motors if I remember correctly, but that could be a mistake so you'd need to check). Basically, you're taking the 4.0 and putting a 4.2 crank in it for the extra long 'stroke'...thus the 'stroker' motor.
Mainly important in any of this is trying to get fuel injection though... sure, the 2100's are great carbs, I love mine for the money I have into it...but FI is the way to go in the long run. 6 or 8 doesn't matter as much to me as good fuel delivery and a strong block, whatever the block may be.
Of course, I have a 305 vortech that I'm putting in mine, but I would have been happy with getting a 4.0 HO with FI also... I just couldn't pass up the deal on this v8, that's why I got it.
you COULD get the 4.0 head with MPI and put that on your 258 you know. That would require you to go through the bottom end of your current motor and make sure it's in good order, I would definately put new rod bearings in and rings of course, but with that setup you'd have plenty of motor to get you going around.
Roger is right in the long run...you gotta figure out if you want to upgrade your axles and stuff with more beef...then based on those upgrades you may want to go ahead and put some more power behind it, or just gear lower
Either way, get an auto.
:biggrin:
