Welcome Craig! I have a 1988 SR500 too, bought it new. I used to have the "Blueberry" paint job, which I finally had to strip off after 32 years of hard riding. These Cannondale frames are made with some hardened aluminum that polishes up quite nicely, with a little work:
Here is the main "Vintage Cannondale" thread, I think it has around 1100 posts:
Show Us Your Vintage Cannondale!