Hey noggin Tom here if your distributor is in the front it is not the poly engine the 318/383 poly or 273 small block these engines had the distributor in the rear if it's a big block the distributor will be at an angle with the cap towards the pass side, if it is a 2 barrel and single exhaust it's probably a 361 same as a later 383 intermediate.back in 63/4 the 383 two barrel was the polysphiricle engine and the 383 four barrel was the big block(intermediate)the difference between an intermediate big block and a wedge is the wedge has a taller deck than the intermediate but most parts interchange except intake manifolds both are concidered bigblocks to identify the engine there should be a pad near the distributor with engine size stamped into it