Been there, done that!
Don't get carried away with a later model 4BBL intake. Your engine MAY be an even-fire, I think they actually started in 1978, but Buick did raise the ports on the 231 around 1979. This means the later 4BBL intake won't fit right on your early 231. They didn't make a factory 4BBL for the early engines.
In the early 80's I had a '75 Skylark SR with the 260 V8 with the infamous Dual-Jet "1/2 Q-Jet". Smoothest running V8 I ever saw but the slowest. Ran 19.7's at the drags. I decided to install a '67(?)225 2BBL V-6 in it. I installed a KBMK1 cam in it and a set of KB shorty headers. It ran an "astounding" 19.3 and a few mph better than the V8. Slow as all heck off the line being shackled by the stock converter and 2.73 gears in a car that weighed near 3600 lbs without me. The hatchback and SR option really added weight. The car was a bit more exciting to drive though because now you could easily rev it up to 5000+ and would actually chirp the tires 1-2 at about 60 mph.
After awhile with that I stepped up to a stock '69 Buick 350 4BBL with mild cam and Hooker headers and with the same driveline it ran 14.4@94.
I piddled around a few years ago with a 252V6 in a '83 Regal Wagon. I replaced the factory 4BBL intake with a Weiand and a mild Wolverine cam and it really woke it up. Never got around to headers. According to my Vericom on the street it went from low 20's to low 19's in the quarter which just made it feel a whole lot better.
What it comes down to is that you can throw a ton of money into a normally aspirated V6 but unless you get serious and rev it up it will never make any decent power. BIG cam, heads, gears and converter plus compression boost will make power but for the cost of a stock 350 you'll probably still be ahead. Weight of the car will always be against you.
Here's what I would do if you wanted to add some excitement to the V6 you have. Weiand, Edelbrock, or KB 4BBL intake. Mild cam upgrade. Headers. Watch the exhaust size. Dual 2" with x-over or at least H-pipe and quiet mufflers will do because the engine won't flow much air and if you go with a louder muffler it will be obnoxiously noisy. V-6's don't sound particularily good when thay are loud. Get a converter into it. Maybe something like a cheap 3000 stall 10" which would be lighter and allow the engine to rev up faster and get you out of the hole quicker. Shift Kit in the trans to add some zing when you shift. Don't forget to recurve the distributer and upgrade the HEI ignition parts. You could also consider after doing the above stuff a small 75-100 HP N2O could be addeed. The engine would take it no problem for occasional use.
I got my later engine stuff off E-Bay so search there.