Well with the combo you desribed, I'd say your quest for the 550 mark is very realistic.
You mentioned stainless rocker arms, I assume your refering to comp cams hi tech pro magnums rocker arms, a good rocker arm no doubt, however, I recommend their latest twist on the pro magnum, which is the ultra pro magnum rocker arms, I also recommend a good rocker arm stud girdle.
On your cam selection, keep in mind that gearing, trans type, converter stall (if auto), intake, carb, tire height, exhaust all play a role in getting the most out of your cam, I'd give comp cams a call.
CC's cam helpline :1-800-999-0853
What are you refering to here?
"I just ordered a rod & custom ifs"
BTW< > I like the torque thrusts, for that old school look.
Cp