I would do some more research on it. The W-Block (348 - 409) can be worth your time, date codes and casting numbers will tell you more about it. The car collectors are always after early GM stuff. It's getting harder to find the "W" parts, so it could have some value. Especially if it did have a forged crank, not sure on that one.
I would think the 4GC Rochester with a governor would only be interesting to a truck guy, they were never used on a car and the carb numbers are different for those without the governor. The distributor is a truck item as well, it probably has a spinner governor inside, most medium duty GM trucks used some sort of weird distributor with a specific oil pump drive configuration, different from the passenger car line.
The exhaust manifolds may be something to check out, if they were used on multi-line vehicles, they could be somewhat more valuable. The thermostat housing is another piece to research. Some early cast-iron housings with the proper casting number are worth a bunch. Again, it depends on the angle of the hose outlet and the numbers.
If you know of any GM car guys, swap meet guys, etc., those are often a good resource to ask. Good luck with it, it could be interesting....:msp_rolleyes: