diethelm
Have to disagree ( with people would prefer an R) I can see no reason to have an R engine unless you live somewhere hot or high. Seeing as loggerman lives in Wales UK which is neither renowned as being hot or high ( Snowdon 3500 ft or there abouts) In fact he would be better off having floats than a C20r as it rains that much in Wales.
All my 500's have had B's and they have never run out of tot before torque.
Having just reread your post I see with your overhaul head on you would prefer a B prey tell why