all I have to say is when buying an old car dont trust anyone about its history

I am merely curious. Does your Ventura have the Chevy 307, or the Buick 350? Or is it the chevy straight six?
I had a early 70s Omega that still had the Olds engine. Anybody that wanted to buy it was hoping for a chevy, so they could swap their "badass" chevy into it.
In fact it was born with a 260 cube 2 bbl Oldsmobile V8, backed by a Th350 and a 10 bolt differential packing a 2.56 gear. Yeah, she's a little road rocket, not!