The B155 on the head is just a Julian Date Code, no need to pay attention to that really. For the 350 engine, MadOgre is talking about a set of 1.94/1.50 size valves. That is the common big valve head size. 2.02's are hipo heads in the late 60's to mid 70's. Rare and hard to find and the gain is not worth having to have all the machine work, new valve seats and cost of the valves to upgrade to 2.02's, not to mentions making the heads more crack prone between valve seats. The 1.94's are pretty common but in a 76cc head. So now you see what 53 cc heads will do for a 350. That will raise the compression ratio to high for those tired rings if you're not going to rebuild the motor.