I'm looking at a 1978 tahiti with a gm 454. The motor is suspose to be factory. It's a 4 hour drive and the guy doesn't want to pull the covers for the head numbers. Did these come with oval or rectangle head ports?

I have a similar year boat with a 454. It has the large oval ports (not peanut heads). I'm not an expert by any means but I'd probably take the leap and assume you are dealing with the same and don't have the rectangle port heads. Hopefully someone with a Tahiti can chime in. If you don't get hits here try the SCJB Facebook group, guys are really responsive there if you need a quick answer.