Roller Rockers

[truckster]

I'm getting close to buttoning up the Vortec 5.7 I'm building for my Blazer. It's a .030 overbored block, decked just enough to clean up the mating surface (about .002), RamJet 350/HT 383 camshaft, new Vortec castings relieved for larger springs. I'll be running a Quadrajet and HEI. As I'm putting it together, I started thinking about roller rockers. The ones I'm considering are the 1.6 Competition Cams 1418-16 Magnum self-aligning roller rockers. I have a few questions for the experts on the board:

1. Comp Cams claims a 15-30 horsepower increase with these rockers. Is that realistic? Can I expect a similar increase in torque, especially in the useful range?

2. Are these good rockers? Is there a better value I should be looking at?

3. Can I use these with my stock pushrods and valve covers? (Comp says the valve covers will clear)

Thanks

David