Crank balance again

Have had a good look through the Forum and read a number of books on the subject. I have my engine in many bits at the moment (52 ES2) so is the ideal opportunity to do something about it if need be. It seems that the push rod engines are balanced to roughly 50% the camshaft engines to 70%. My intention is to run my ES2 in the 50/60 mph speed range. So my question is, are the camshaft engines smoother than the push rod engines at the aforementioned speeds or does the benefit only really become noticeable at higher engine revolutions. I found, before stripping the engine, that vibration was quite harsh at 50 and above. Engine is in generally good condition apart from a slack big end. John