360 heads on a 318 LA

68-69 340s had X heads...
70-71 340 had J heads with 2.02 intakes..
72-73 340 had J heads with .188 intakes

all 360s had what would be basically J heads...1.88 intake valves..all about the same peformance..some had air injector ports...some did not...some had U, Z, O casting but their performance is in line with the J heads..

i have a set of J heads that can milled down to 59 cc....and they fit fine on a domed piston..... with a positive deck piston you adjust the head gasket..

In fact..NHRA blue print spec for a early 340 is 63.3 cc...which means that head has been milled quite a bit...and the pistons blue print spec is +.045 out of the deck....