Big cam ='s low manifold vacuum at idle. You want the primary metering rods to stay down lean at idle.
Therefore a low 3" 4" power step spring. Similar to holley power valve selection.
The distributor will need to be locked out with either carb. The edelbrock carb will work fine once the distributor is corrected.
This is the nature of these big racy cams.
edelbrock carb tuning
Volvord 784VC Edelbrock Carburetor
Don't bother with a vac sec carb.