I've done both. Started with a well built 292, this is the engine Tom ended up using on the dyno last year.
It made maybe 210/220 HP and drank gas like a semi. After all said and done this was a $6000 engine by the time I bought every thing for it. Machine work up here is expensive.
Flip side I put in a 2005 stock 4200, made 275 HP got 26-28 MPG on the highway and just went like stink compared to the 292 once you got it wound up a bit. The 292 had more bottom end grunt up to 2200.
Then I put a turbo on the stock 4200 at 7 psi made darn close to 400 RWHP. Still got good mileage.
A good 4200 with all the wiring etc can be had for 1100 to $1500. Jeremy charges $99 to reprogram the PCM. You didn't mention what you have or want to run for a trans so I can't comment. Any 2002 up to 2008 4L60e that came behind a LS will work with a bell housing swap.
Mounts etc you can make. Reuse your 3" exhaust - just move it to the other side of the car.
Someone here will most likely buy your iron6 speed parts. Most likely get $300 to 400 for them.
By the time you rebuild the 250 your way ahead with a 4200 - turbo it and you have a solid 400 hp to go play with.
Last edited by efi-diy; 06/13/12 11:16 PM.
