Clean Looking Ventura, has the upgraded Custom Package, looks to be powered by a Olds 260 V8. The stripe package on it was probably optional as it looks identical to the "Sprint" exterior marking without the Sprint Logo's. High option car on the outside, pretty basic on the inside. Interesting car. Is it worth the $8000.00 asking price. https://nmi.craigslist.org/cto/d/alpena-pontiac-ventura/6965058179.html
I've warmed up a bit to the '75+ X-Body cars over the years. I used to hate them. The '73-'74 Novas always looked so frumpy when they went to the bigger bumpers. The BOP versions look much better in my opinion. This one looks pretty nice and I like the stripe package. I think you are right on the engine. It looks like the 260 was the only Olds engine installed in these. Easy enough to put a 350 in there.
It is now down to a more reasonable asking price of $6800.00 https://nmi.craigslist.org/cto/d/cadillac-1975-pontiac-ventura/6982458582.html