340 heads on a 318?

wow.lol

I agree the 340/360 heads should be milled to raise the compression, they are 72'ish cc's from the factory with 318 heads 'open chamber' version being 68'ish cc's. in that case 'if it were me'...I would be looking to remove about .050 from the decks, 'every .0048 removed is 1 cc' on a 340/360 head fwiw. food for thought, when going from a stock steel .019 thick head gasket to a felpro replacement style, you just added .026-.028 more to the gaskets thickness and just gained 4-5 cc's-'lower compression'
So with milling off .050...you end up with about 61cc's but thats also compensating for the thicker head gasket by doing so...so it's the effect of 65cc chamber based on a .019 gasket, if that makes sense.... after the decks have .050 removed, also do the intake face of the heads, remove .045..., there are diff thickness intake gaskets to work after that.

I also like the engine quest head idea if the money is there, i hear they flow about 10 cfm more than a 2.02 x/j head and still have a small'ish port volume, but wouldnt want them for more than a 318-330 cid in comparison to the other heads available.