I guess you are talking about the "old" 16/17r? they are a pretty skinny boat and are often fitted with big motors, so, they all look stern heavy, even with a light 90 Yamaha 2 stroke they look down at the back, but, they go OK, can't say I have seen one with an underfloor tank from new, lots have them because the floor has been replaced. Rather than convert one to a centre console, just look for an original cc, you see them now and then.