I have seen some 4v heads for sale locally. So I will see some significant power starting at 3500? I thought 4v heads made power even higher. I dont mind making power up high. This is going to be a street car with a few strip days...i am sure that even with low end torque being lower than a 2v it still wont be a slouch when i get it to 50-60 mph. Plus i mostly see people running 2v on the street, would be nice to have something different.
Suggestions on cams? Also, machime work required for 4v screw in studs, bigger valves?
If you replace the rod end nuts and make some oiling mods, you should be able to wind your Cleveland to 7,000 RPM. And this would take advantage of the 4V heads. With more mods, you could take the RPMs even higher and the 4V heads will still keep screaming. If you're not going to wind your Cleveland past 6,000 RPM, you'd probably be better off with the 2V heads.
Be aware that a lot of people will say they ran 4V heads on the street and the engine was a dog at low RPMs. This is a common issue. But I think it's mostly because the engine wasn't built correctly and the rear gear was too small. For example, you can't use a cam that has a grind designed for a 350 Chevy. It won't work well in a Cleveland. (Up at 6,500 feet above sea level, where I live, it's difficult to get good results from the 4V heads. That's why I went with the Aussie heads.)
These days, engines that immediately come on strong and have a lot of "grunt" are popular. You're not going to get that with 4V heads. But it doesn't mean the engine will be a dog at lower RPMs either.
Think carefully about your build and plan everything out. I would also recommend you sign up over at the 351 Cleveland forum. The people there have a lot of experience with the Cleveland. You'll find guys who run the 2V and the 4V heads on the street and on the strip.
For a cam, a hydraulic version of the Boss 351 cam would probably work well for you. But definitely ask on the 351 Cleveland forum.
Don't forget, the 1971 Boss 351 Mustang was the fastest factory Mustang in the 1/4 mile. The Boss 351 engine had 4V heads. I've never driven a Boss 351, but I've never heard of someone who has driven one complaining about low end performance.