Stock 72 318 power gains

One of the big games of the 318 heads is when you have them reconditioned with seats see job guides in different order of course also ask for the valves to be back cut. Does valves have a tremendous ski-jump on them. At the moment I'm in the market for a new valve grinder, used but new to me, so in the 30 to head video I wanted to show a back cut along with the chamber and valve job work but I'm not able to at the moment. I feel that alone would add another 4-7cfm.