I did the swap on my old pump gas Duster 505 C.I. low deck six pack pump gas motor from a set of ported and polished big valve 906 to a set of CNC ported Eddy RPM, that car picked up a solid two tenths and 3 MPH in the 1/4 with the exact same compression ratio.
I change the crank stroke by .050 (4.250 to 4.300)the next winter to go from 9.25 to 1 to 10.29 to 1 compression and that picked up the car some more
On your deal go with some good heads like the Eddy RPM with the 84.0 CC combustion chambers or the other set with the smaller 75.0 CC chambers, do the math on which heads give you which compression ratio, I wouldn't go above 10.75 to 1 or higher on todays pump gas
IHThs, six packs rock