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.
No. The bore size is different between a 305 and 350. The 350 bore size is larger.
the block & heads are the same you just have to pull the 305 out & put the 350 back in
Yes, but running a 350 cam with 305 heads is not effective,you need to run 350 heads as well. In order to benefit from a 350 cam you need something to flow that extra fuel and air, so using 350 heads along side of the 350 cam will be the cheapest and best choice. HAVE FUN!! A 350 head can physically bolt onto a 305 block. However, 350 heads can have the valves extend into the cylinder and contact the cylinder wall (even with the smaller 305 cam). The 350 cam in the 305 with stock heads will work. You wont want to use 350 heads you will lose compression due to the largers combustion chambers.
305 heads of course, 350 heads will fit for sure and possibly 400. obviously no big block heads will fit. a 305 with 400 heads gets you a little over 352. 350 with 400 heads is a 383. add and divide
You will need to have the heads for the 305 bored out to the same size as the 350. I disagree: you can use the 305 heads on the 350 block but you will increase compression as the 305 heads have a smaller combustion chamber. The critical dimension is valve clearance. If compression ratio is a critical consideration, different pistons may be available which will bring the combustion chamber back to size. the 305 is from the 3.671 inch bore family. The 350 is from the 4.00 inch bore family. All small block heads have the same bolt pattern.
305 327 350 400 283 with a little modifications
No. The 350 has bigger valves. While you CAN put the 305 heads on the 350, (I can't imagine why you would actually want to) you can NOT put the 350 heads on the 305. Because of the 305's small bore, the valves on the 350 heads will hit the cylinder block.
That depends on what type of heads are on each, and the year it was built.
The 350 engine was introduced in 1968. A 1955 small block would be a 265 or 283.
Yes and no. They will bolt on and probably perform maginally better because of an increase in compression, but 283s were never intended to run on unleaded gas so the exhaust valve seats won't last. The 283 used 64cc combustion chambers and the 305 used 76 cc, so you are going to probably have to go to the nest higher octane gas. You'd be better off getting some dime-a-dozen 305 heads from a wrecking yard. A word of warning. Don't try to use heads with 2.02/1.60 valves from a 327 or a 350 on a 283 or a 305. The valves hit the block!!
If the Buick 305 is really a Chevy 305, then the motor mounts will interchange with a Chevy 350.