You don't HAVE to go with a hydraulic roller block. I am running a 1990 block and using those retrofit hydraulic roller lifters, but they are pricey. Yes, the pre '74 blocks are stronger, but post 74 351 blocks are still plenty strong for some 'serious horsepower'. I'm putting 530 down at the wheels right now and nothing's blown up yet. Going to put on a smaller pulley soon, so we'll see how that goes. I was 600 RWHP or bust!
ANd pokageek is correct, to do it right, it takes some serious money. Keep looking around, the information is out there.
I'll chime in here, even though I'm the baby of the family with 404hp @ 5700rpm running a NA 357.
A tremendous amount of info can also be gleaned by searching the stangnet, corral and turbomustang. Also look at eec programmers or management systems; which will be required to get the EFI to work.
When posting my 351w swap experiences, I tried to provide useful info within the threads for others doing searchs. Little things, such as wiring, electrical, fuel delivery and cooling will eat up your time and wallet.
I even have traction problems and will be moving up to a drag radial. Problem with standard street tires is that they let go and start spinning fast with no or little warning.
My turbo 357 Gen 1 Lightning just made 502/635 and it's fine. It has stock roller block, stock crank, forged pistons and H beam rods.
Our turbo '95 Mustang just made 640 with boost problems - fixed it should be close or over 700. No issues with block failure - many people regularly go over 700 to the tires with them. These are all 94-96 roller blocks.
If you are doing a turbo, plan it carefully, I do not suggest going to big cubes - maybe 351-357 - mainly because of the huge exhaust volume they make. It creates pressure ratio problems. Although with twins it shouldn't be as bad as a big single, but you still need to plan carefully. You will need a big oil pan and a high volume pump or you'll have oil pressure problems at the top end of the track.
Don