70" 340 vs 72" 340 specs please

pistons were changed...compression height changed from 70 340 with a 1.84 to about 72 340 with a 1.74.....

cylinder heads changed from 2.02 intake valve to 1.88 intake valve

carb/intake change....70 340 had carter avs carb with square bore intake manifold...72 340 used carter Thermoquad with spreed bore intake manifold...