Two pieces of angle iron, welded into a "Z" shape, will allow you to create enough clearance for any reasonable-size balancer, (and belt) even the one with the huge rotating weight, by using tubular risers to support the regular attaching points of the 235 flat engine support. The 250 engine balancer has belt groove(s) machined into the external balance ring, not a separate pulley and weight. I would choose that option for two reasons- - - -it can be bought brand new, and with only a slight modification, will align the narrow belt with the water pump and whatever charging system you choose to use. If you use the 2-sheave item, accessories such as air conditioning or power steering can be adapted later, if you choose to do so. I have done all of the above on a few engines, so I'm not just blowing smoke. I wish you the best with whatever method you choose to try. With a little creative metal whittling, it would also be possible to fit a serpentine belt system with a spring-loaded tensioner that would be even smaller diameter.
Jerry
