I've had a few 64 and 65 Oldsmobile Cutlass cars with the stock 330 Oldsmobile engines. These engines are very streetable as-is. I never ran anything but the stock cams, heads, exhaust and 2 barrel intakes/carbs and was satisfied with the performance. I even had a 330 in an oval track race car, and thought it performed well...plus was VERY durable.
I would think that even if you just swapped in the 330 for the 307 without even rebuilding it, you'd be pleasantly surprised at how much better your Cutlass would perform.
I don't know first hand, having never had cars with 350, 403 or 455 engines, but the 330 is suposed to have the best throttle response of the Oldsmobile engines. The 330 was the original design for the small block Olds and it is a nice bore/stroke combination for all-around performance. I think it was increased to 350 mainly because GM's marketing wanted Olds to have a 350 to compete with the other makes of the time.
The 45 degree lifter bank angle does require a camshaft that is usually not stocked by most parts dealers and the pistons are a bit tough to find in stock too (and more expensive than 350 pistons). You might not find the 10.25 compression pistons without going to an expensive forged piston. Even if you rebuild, there is a good chance that you'll be able to re-use the pistons and camshaft if the engine isn't too worn-out.
One thing to be aware of, is the fact that most Oldsmobile V-8's had non-adjustable rocker arms. Sometimes you need to get custom legnth push rods if the heads and block have been milled. Or, you could get adjustable rocker arms from an Oldsmobile specialty shop. Again, if the rebuild is mainly just rings, bearings, gaskets, etc... you don't need to worry about it.