Nutbar51,
I've been away for a while. More than likely when you get the engine apart you will find that it is a cast crank, either made by 'Scat' or 'Eagle'. A forged crank would have cost quite a bit and usually an all-out-racer can afford it. The is no way to visibly tell if it is a 383 or not other than to measure the length of the stroke (or travel) of the piston as it goes up and down the cylinder wall.
For a bit of clarification: Using the 400 crank was 'old school" and was done when the 383 was somewhat experimental. It required extensive machine work to cut the crank down so it would be able to use the small rod and main bearings. Then, the crank had to be hardened again. This was all quite expensive. Nowadays, you can just purchase the 383 crank in a stroker kit for less than $800. The forged crank kit took it up to around 2K to 4K depending on what all you wanted in the kit (see what I mean on the expense?).
Another way to tell if it has been stroked is to look at the block to see if it has been ground on the oil pan mounting surface for clearance. The 383 has 1/4" longer stroke than the 350, therefore it requires more clearance (usually about an extra 1/8th inch on each side of the block). If it has been ground it will be very obvious.
If it is running badly enough that you have to tear it down, it would be a good time to look it over. I am not sure what you are referring to on needing a harness... depends on the application.
