340 Heads on a 273 Block

I would install late model 318 heads with a port volume of 138-140 with the 1.780 intake valves and just do some match and port work on the bowls and be able to still use the stock rocker assembly or go to a adjustable rockers.The 340 head with kill the small motor of 275 and the port volume is to much for your applacation.And if you did get a set of the 340 heads with the smaller valves it would still be to much.To keep the volocity up and the the cylinder capable of filling close to 100%and with a good dual plane intake and small 4 bbl carb,this will work great,Mrmopartech :salut: