nothing wrong with the Edelbrock bases that Ive worked on and done a bunch of them. Prefer the Accel a little better but if you have an Edelbrock go for it. Better than the stock one I can assure you of that. Dont worry about core shift, if any thats what grinders are for.
Ill have some flow results on both ported to the casting limits and bone stock castings in about a month for you guys.
Corvette 40 you can really dig into those castings. On the head side the last few inches is a bad pinch point go to town so if looking in there at a 45 deg angle you want to straighten out the line of sight.