want too up grade my 94' 5.0efi bronco.but dont want to have too pull the block out.i want about 300-375hp.buget is around $2500.ive put top-in kits on my early broncos,but there not efi motors.just not sure on this efi motors.
Best piece of advise I can give you is to get over your not wanting to pull the block. 375 HP will definitely need work done on the bottom end, like a forged crank, and you're not going to do that with the motor in place. The bonus is that it will be way easier to swap the heads, cam, etc with the block out and on a stand.
There is a recent article in Muscle Mustang and Fast Fords magazine on this very subject, i.e. more or less stock EFI 5.0L build from mild to wild. The Bronco EFI 5.0L is very similar to the mild engine they started with. You can see the stock E7 heads are the biggest limiting factor keeping the engine around 310 HP. The cam required to get there is a little on the wild side for a truck using Speed Density IMHO. Once they started using aftermarket heads the real pay off began.
You could get close to your lower HP goal using aftermarket heads, free flowing exhaust and some tuning.