The 509 will make more H.P. and less torque than the 528 in an engine with a real 10-10.5 comp ratio.If it's too low the .509 is a just a noise maker.The latest .509 and the .484 with the revised LC have much better street manners.
The last engine I built with a 509 was 20+ years ago, forged TRW sixpack pistons, 915 heads, a true 10.5 motor...The 509 was such a dog down low I put Rhoades lifters on it which helped tremedously but it sounded like a race boat the lifters were twice as loud as a well adjusted solid lifter....
I've taken 509 cams out of four cars & only installed two, both times I felt there were better cams out there....
