Cast iron 4bbl intake differences between 340 vs 360

both equally good intakes. the 1970 340 intake is for a square bore carb, like an afb or avs or most holley, I had one stock on a 1970 340 Duster and it had A. C. the 360 intake is for a spreadbore carb, like thermoquad or quadrajet and some holleys. you can make a blockoff plate for the e.g.r.