Holley owns Quick Fuel Technologies and BG Fuel Systems (Demon). Except for the Street Demon, all of the four-barrel carbs being sold by the three companies are based on the same Holley design. If you can work on a Holley you can work on the other two.

As far as rockers go, stockers are light and cheap. There have been many many bigblocks built with the .509 lift cam and stock rockers. Your suggested cam is in that ballpark for lift and that's where I'd go. Most cheap aluminum rockers are cheap and don't work well or for long. You may want to find AndyF's article on bigblock rockers, seems like some of them don't fit too well. Many have had good luck with Harland Sharps, I believe Hughes sells the plain bearing set. Otherwise I'd stick to known brands.

R.