A cylinder is misfiring.
That would be a small block.
No. You would need to have the main journals turned down .200". Then it would fit.
no modifications necessary
Many. 348 would be a small block, whereas the 454 is a big block.
Everything
That would be a big block. If you are referring to the diesel engine, it is based on the Oldsmobile rocket block, and shares nothing with the engines usually referred to as big block or small block.
The 350 is the small block, and in 1986 it would be GM corporate blue.
no
One of the valve covers.
It would never hold together.....
Lack of lubrication.
Yes