Use the .620 w/1.6 rockers = .661/275+@.050 with your weight/tyre/theoretical hp combo and 4.56's you'll be turning around 7k in the traps with slip, 4.88 will be near 7500 which would test even that cams abilities at the stripe.....2c's
you could also have a read of this talking about the 290/650>
