Could be any number of thing, be a little more specific about how it is acting or doing. Fuel, compression, spark plugs, plug wires, battery, connections, starter.
No real problems it is a solid engine.
Who said it won't ? It will fit right in there with NO problems
Yes it will with no problems.
YES, It will bolt right up with no problems.
If the Buick 305 is really a Chevy 305, then the motor mounts will interchange with a Chevy 350.
Oldsmobile used Chevy 305's. 76 350 rocket 77 305 Chevy
There is no information on the internet about what the special feature of the Chevy 305 engine is, in fact, the Chevy 305 and 350 are interchangeable, one is just an older model.
305 horsepower
As long as the 350 is older then a 1987, you will have no problems. They will bolt right on with no modifying.
The headers for a 350 and 305 are the same.
YES they are the same.
How much money do you have? The 305 Chevy is not a good starting point. You would be much better off finding a good 350 and work with that small block. The power is only limited by the amount of money you want to spend.