I think the best Crate engine that would suit your needs is the GM performance parts 350 HO Deluxe crate engine, it's not the full 350 HP minimum you listed but 330 HP, still should provide adaquate MPG and it is 3,495.95. yes the motor mounts will work. I don't know of any other FI crate engine. Probably with a diffrent cam and valvetrain upgrades to match, that 350 HO deluxe would probably touch 350 HP