Timing is 4 degrees B.T.C. on both, but Not knowing the Year & Correct size, that is what the book shows for most 70's........
It would be best if you would get the Numbers:
Pad on Front Righthand side of Cylinder Block at Rear of Distributor....
Auto Mech / Electr&onics
Chevrolet Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics.