J head question

I would rather have a 915 "j" with the smaller 1.88, this way your assured the valve will be up high when you install your new 2.02 valve. if its a stock 2.02 head thats had several V/J's the valve will be sunk low into the head = poor low lift flow. Just my two cents... Also you would have to look at the cast date code on the head my j's 2.02 are like 3600 = 360=360th day. 0= 70 if you see a 1201 or something like that would be 120th day of 71 so it would be for a very late 71 and 72 car with a 1.88 valve.