The easiest way I can think of for you to identify difference would be to take some physical measurements. Grab your trusty tape measure and measure the distance between the crankshaft snout (balancer bolt) and the DECK of the block (where the head gasket is). Now, you'll have to kind of hold the tape measure out a bit, but if it reads close to 8.2 inches, you've got yourself a 289 or 302. If it measures close to 9.5 inches, you've got a 351 Windsor. What may even be easier would be measuring the distance between both front intake manifold bolts of a known 302 and comparing to the motor in question. The 351 Windsor uses a wider intake due to the taller deck height. Best I can offer.