Go with the 8.8. It will handle the HP and is easier to drive (read takes less HP) than the 9". If you have to just get a different offset on your rims to compensate for the narrower axle.
unfortunatly i already have my wheels and tires, i could do spacers, i also already have an 8.8 LSD with 3.73's. 4.10's would be too low for my application, 3.73's mite be as well, if i go 5 speed, id prolly need to stick with the 3.55's