I agree with Uncle Brad (and, Dave), why not try to start it up?
However, the carburetor might be a problem, from sitting too long.
If you are looking to rebuild it (or, have it rebuilt) and then intend to sell it, I agree you will not get your money back (on a stovebolt or any other engine), unless you an professional engine-shop that can provide a written warranty.
If you intend to use that 261 (or, another stovebolt engine), rebuilding the 261 is no more expensive than rebuilding a 216/235.
