Wylee, It appears you have the head off one side. It should be fairly easy to measure the stroke. If it is 3 inches that will tell you. It couldn't possibly be a 283 as they were not made with 4 bolt mains. The harmonic balancer appears to be factory and that size balancer only came on the 302. That said, the condition of block, crank, pistons and rods are of most importance. It also appears that motor has been into or rebuilt as have most that age. I would have a "trustworthy" machine shop examine the afore mentioned parts. The main draw-back with these motors is parts availability and cost. But to those of us who know and love those motors for what they were, it's $ well spent. Robert