I must concur with 3B on the engine size as far as original goes. I've never seen anything smaller than a C60 with an optional larger V8 which would have been the 366 CID. It "looks" like a larger 427 and shares the same block design. Of course it could have been changed so who knows. All truck 427's were tall deck motors and the cars were shorter deck heigths so that may account for your confusion.
I'll do some research on the Tulsa winch for you as I've sold them and repaired a few over the years so maybe something will turn up. I think it is a straight PTO drive, i.e., not a hydraulic driven winch. Does it have a forward and reverse PTO?
