[Surfster]

I see some of you guys using Colorado blades for lips on Surfsters and such. I finally found them in the Netcraft catalog. Now I'm just trying to decide on size. The #7 looks to be about right. I plan on using them on 2.5oz Surfsters that are about 6.25"oal and 1.4" in dia. Am I on the right track or do I need bigger / smaller?

Thanks