Should I order the 7" cutout or the 9" cutout?

I want to buy a Poptop to go with my Memphis Slim, which I bought used. It has no visible part numbers. The headlight itself is 7 inches but the cowl makes the whole thing about 8 inches across. I measured the cutout on my Slim and it is about 8 1/2 inches across. I'm guessing mine is for the 7" headlight. Whadda you guys/gals think? Don't make me call Mary Evans.

Thanks in advance.
Cody

I was born a long ways from where I was supposed to be. - Bob Dylan