Bulova would not have sold movts or dials to other companies, but as mentioned, there were after market cases and dials available for worn out or cosmetically damaged ones.
If the watch has not been serviced within the last 6 years, it will need to be serviced. 99.9% of all the watches I see have not been serviced in many years. If they are dried out and dirty, simply running them will cause accelerated wear. The movement, as I'm sure you know, is a micro-mechanical device with metal on metal wear as well as metal on jewel. Even a jewel can be worn when dirt is present and acts as an abrasive.
When the quartz crisis hit in the 70's old mechanical watches were forgotten for many years, as the maintenance and price was far higher than the new cheap quartz watches. The main reason anyone restores an old watch is because of sentimental or heirloom value, but hang onto it long enough and it will increase in value. In the vintage watch world, Bulovas are very underrated.