Kenny, it sounds to me like you could spend another $1000 on that thing in a hurry by the time you put tires all around, maybe rear rims, and tighten up the steering. That thing better run like a jewel to be worth over $1000 from your description!
With the wrong emblem on the front, and no serial tag, you'll have to do a little detective work to determine what you have. If I'm understanding your description, the starter button is actuated by a rod THROUGH the steering support post? I think that's a feature that disappeared sometime in the mid-40s. My 49 M and 52 SM both have the starter button actuated by a lever (rod) that you press down with your toe, but it goes around the right side of the post, not through it.
As to distinguishing the M and SM from each other, the SM will have disk brakes (cast-iron housings with bolts through them) and the M will (usually) have sheetmetal covers over the band-type brakes. A few late M models had the later disk brakes, and there was an option for a different type of disk brake even back into the early 40s.
See if you can scrape off enough dirt and read some casting codes on the engine, transmission housing, axles, wheels, etc. This is probably the best way to determine if it was assembled at the factory, or out of someone's parts pile.