I shopped around on my latest build, and went with Harland Sharps based on previous good experience. Roller rockers usually hit the stock valve cover oil baffles, but we make a valve cover spacer for that if you want to avoid modifying your baffles.
If you want to run spark plugs with a 13/16" hex, you'll need to grind a bit around the plug locations: mock that up before assembly.
Somewhere - either here or at moparclassifieds.com - someone's selling a set of HS rockers & shafts cheap.