It should work fine. Make sure it is in a working shutter and not a barrel lens or it could be a surprise you didn't want. There are many faster 300mm lenses from a variety of manufactures in your price range. Maybe put a wanted add in the classified section and see what you get. I had one of the 12" RDA's and it was perfectly fine, but there are certainly any number of 12"er's that are much faster (larger also).
regards
erik