ps, when I did a lot of 318 heads...after working them to 210 cfm with a stock 1.78 valve...opening the port window to a 360 size was only worth about 4-6 cfm on the intake side. Don't do it on the exhaust or you'll hurt flow.
Yeah, I only gasket match the 318 head intake port opening to the 318 gasket, not a 360. I also agree, hogging the exhaust exit port isn't the key, but I do clean up the casting around it on the inside, which may open it up a couple of thousands.
