It won't fit a Poly, as the Poly's are I-E-I-E-I-E-I-E and the Wedges are E-I-I-E-E-I-I-E. There was a bolt hole issue with the early 273's (different angle of the bolt holes or something like that) but there is a good chance that with little to no modification it would work on a 318 head as well. That said, if you really want to use it, I would consider something along the lines of hotroddave40's 318 build...but you can choose how "economical" you want to make it as far as cam/carbs are concerned. A couple 450cfm vacuum secondary 4-bbls would be a max effort, but a 302 headed 318 is capable of some decent snort without breaking the bank.

Just a thought...