Last B1 Original we did, last year, was 540", heads with alot of work done, 420cfm, 2.300 x 1.78, Ti, cam I picked (kind of large roller, around 280-294@ .050, .870 lift gross on intake), 14.7:1, Q16, 1150, KB block, B1 intake I ported...Made 970HP and 825TQ using customers headers (2 1/4 step to 2 3/8, 30" long, 4.5 merge collector). Was a very nice combo, smooth lobes on the cam, made power at 7000 and carried to 7300rpm.
I think maybe tuneup is part of it, but heads sound like the problem...and maybe the Tunnel ram. The ram would have to be right (and the heads) to make great power on a 572.