OK. I see the pull-out knob now. So it is a 101.07403. Unfortunately, some PO removed the nameplate presumably from the right end of the bed.
Well, from the rectangular instead of oval motor switch bezel, it is probably 1948 or later. Atlas changed the 10" headstock casting circa 1942. But the Craftsman catalog and other photos continue to show the over switch plate up through w947. So we don't really know what year the change was made to the 12" headstock casting. Unless someone with an earlier bearing date should pipe up. In the meantime, it was built between 1948 and mid-1957.
Beyond that, the only other way to date your machine is to pull the spindle and report the four dates on the two bearing cups and cones. And use the latest of the four dates. If there are no dates, then it was built after mid-1952 up through mid-1957.
WRT the 1HP motor, that is considerable overkill. Factory recommendation was 1/2 HP. The larger motor won't increase the capabilities any and on the down side, if you ever do have a crash, the larger motor will likely do more damage.