hello. i've checked several sites and they are split 70/30. 70% list it as a 350 truck engine. and a couple list it to be out of a car... like a caprice. the engine WILL work in your application fine.
without more #'s off of the blocks cylinder head deck surface... that's as specific as i can get. below is an excerpt from one site.
10054727...350...86-up...2 or 4 bolt main...one piece rear seal, some "Made in Canada"