Re: 327 Vortec vs 350
Your neighbor may work for GM, however he doesnt appear to know anything about GM engines.
your neighbor is either trying to sell you a really old engine (gen 1 327's were built from 1962 - 1969) or he is talking the new LS 5.3 liter which is NOT the same engine and there are no marinized 5.3 liters. There are Marinized 6.0 and 6.2 LS engines.
If you were to look into the new LS based Marine engines you would need a complete engine complete from spark arrestor to exhaust manifolds and coupling along with the fuel system as these are fuel injected and in some cases supercharged. Vortec is a term used by GM to describe both an engine family, as well as a generic name they have given to all engines for marketing purposes. A true vortec technically uses the vortec cylinder heads. It is a gen 1 cylinder head revised for standard cooling. GM had taken the LT1/LT4 combustion chambers and recasted a head to not need the reverse cooling. True vortec engines are 1996 to 2000 model year trucks, and 1996 to present GM industrial engines (which also include the marine engines). These heads were made for both the 305 and 350 engines, however do not interchange them. the 305 head has a smaller combustion chamber and small valves.
your existing engine is a pre 1986 Generation 1 chevrolet 350. you will need to get a pre 1986 generation 1 engine to replace it. you can replace it with a 1986 and newer engine, however you also will need a different flywheel and coupler since GM changed the crank and flywheel pattern. If you go with a true Vortec engine or vortec heads, you will need a new intake as well.
you can get your engine completely rebuilt at most machine shops for $1500. In many cases you can get good heads dirt cheep from your local salvage yard, look for a 1980-1985 GM truck.
