You haven't seen it or you seen it an couldn't tell. If you have a poly block set a wedge head on it an see for yourself. You can bore to 4" and use the 4" crank for a 318/340 in the poly also. You will of course have to notch the stroker pistons for the poly valves. Or put the poly cam, heads and intake on a 360, that should make some bottom end power. 318 poly blocks are a thick wall casting that was used to make the 340 blocks in later years. Poly 318 cranks are all forged steel cranks that work in 273, 318 and 340 with a rebalancing of course. People dropped the poly like a hot potato but it has a lot of potential, especially when you stroke it.