vortec vs non-vortec exhaust bolt up
 

The 4.3L in my boat just died, and I'd like to put a newer engine in. The engine that is in there now is a 1985 or 1986 (the boat is 1986). I don't want to replace the exhaust manifolds. Can I put in a vortec and ahve the exhaust manifolds bolt up? Or do I have to go pre-vortec? Also, are the motor mount positions the same?

Thanks,

John.