I have a stock set of GN1 alluminum heads and need to buy some roller rockers for them. I have a 220/224 cam, ported intake, 20 over Wiesco pistons, k-1 rods, good crank and a 67 bb turbo. I am trying to figure out whether to use a 1.55 ratio or a 1.65 ratio. Any help would be great. Thanks,