Those are nice looking down pipes, what diameter? I am also for any different motor swaps in cars. Haven't had much to do with the small bore Buick and Pontiac 350's. I have only driven one Buick 350 car, a Lesabre from 1980, the last year offered. I remember my old boss saying they were shitty engines when it came in the shop. My other boss had issues with his rebuilt Buick 455 and low oil pressure. Pretty sure a new TA front cover and oil pump would have fixed it.
Downpipes are 2-1/2". They're made specifically for a Buick 350 in a G-Body, and they fit perfectly.
I know all about the low oil pressure stuff & there are several modifications that can be made to increase it, but for a stock daily driver like mine, consensus is that it's not necessary. Just to be safe, I put in a booster plate & new gears.
I would've liked to make this car all Pontiac but I wanted my first swap to be the 'easy one'.