I had a used set of Harlan Sharp rockers on my 440-1 heads with a 690 lift cam and I wouldn't want to know how many runs I have on them. And like I said they were used when I bought my first set of Indy heads. On our small blocks I run 1.6's and my son runs 1.5's with zero issues other than the fact for some reason we had to shim Matt's up a hair to get a nicer sweep pattern. Give Todd at Competition Wedge a call and he will fix you up. I do recommend aluminum spacers and the aluminum hold-downs are really nice.