slant six with offy 4bbl intake

[wicked872]

found one for sale on craigs list, duluth mn $675.00 with rebuilt 904,has on a test stand so can hear it run, been a long time, is this a good price

[peg leg]

You're close, go look and check it out. If it is only a manifold and carb., with no internal mods, It seems high to me. I'd also be wary of a "rebuilt" 904. Takes more than that money for a proper rebuild, unless the owner did the job himself.
On the good side, listen to it run, in person, and decide.