A friend had a 572 with the small port b1ba(?) Heads, shifted at 6200, should be geared to go 6400 in the traps. I bet your SR heads on a 572 would do the same. A lot depends on how much$$ you are willing to throw at this motor to go fast. I would start with the biggest short block you can build, up to 572. Next, how much do you want to throw at the topend? If you want serious power, a jump to B1Mc or predator heads would be my choice, with B1mc's being less$ than predators , but still capable of 1050 hp.
There is only about a 50 hp difference between SRs fully ported and 440-1s fully ported, and the best valvetrain for -1s fairly costly, but you can use the same pistons as your SRs. So the crux of the matter is for serious hp increases lots more parts need to be changed. My choice would be a 572 with b1mc heads, the cam you have, new headers.