[Desperado]

ok i just purchased a set of gt40 heads and the 1.72 factory crane roller rockers from a 94 cobra. i will be bolting these onto my 87 mustang. will i need to shim the rockers or get different push rods or will my stock push rods work with them. the pedistals and bolts come with the rockers that were used on the gt40's in the cobra.

also what kind of power increase is normal for swaping e7's out with gt40's and the 1.72 roller rockers?