Would spend the money to have a full inspection from a third party licensed individual. Seems like you could get something a bit newer for that money. From what I know Cobolts are well built, a bit heavy. I see the one you are looking at has bottom paint, and TRS drives. Parts for those are getting more costly.
Just my .02
Saw this 91 Scarab with 454 and Bravos on a trailer. The ad online says 32,500, but I have seen it in the Boattrader for 30,000 obo. By the way the ad indicates it is a single, but it is a twin 454\B1 boat. Look at the pics.