What engine do I have?

[Duke of Earl]

29 closed cab mod a pickup. Titled vin# A2252539 engine has no number on a machined plate 3 1/4 x 7/8. Engine also has no oil return tube, solid valve cover and a plate over what looks like a fuel pump mount. Timing cover is same as 29 stock cover, Simmons super power head that's marked for model a. Runs great and hate taking it down to try to find out what it is. Could this be a model b block?
Are parts interchangeable between them?
Are there any other differences I can look for on the outside?
Thanks, George