Oil filter access. What are your plans on accessing the oil filter considering the frame rail hides or prevents access to that top bolt? I just removed the 1970 R75/5 motor from my 1961 R50. Of the three bolts the bottom two were tight as you would expect, the top one was a shortened hex bolt and barely in the threads. There was also a gasket. My thinking is this...on /7 models the filter cover plays a role of sealing up and holding the filter tight in canister, hence the white rubber ring and metal shim, you need this snug fit in order to create the oil flow through the filter. In a /5 and /6 the filter cover is actually inside the engine case and held tight against the filter with a 17mm head on the bolt or is it a 14mm, either way, the outer cover on the engine case does not contact the filter. I am guessing the cover simply prevents oil from splashing out of the case and the pressure may be relatively low compared to the pressure inside the canister. So a simple gasket and maybe just the two lower bolts are enough to seal it up. If that is the case the frame does not need any attention. I have seen frames that had a "bend" or an indent on the outside of the tubing to accommodate the upper 3rd bolt on the oil filter cover. That would be my preference, but how would you go about putting that I sent in there? Maybe those frames were holding a /7 engine. I got my engine out and checking the serial number on realoem found the case to be a 1970 R50 bottom end and the guy installed the 750 jugs. I am trying to avoid mission creep...it's so hard! I decided to not break into the engine, not very much...I will pull clutch and flywheel to check conditions and any rear main leak, probably replace that oil seal, basically same process on front of engine, take a peak, check timing chain. My a bike has a complete/5 wiring harness into a /5 headlight shell. Thanks everyone here for the interesting comments, it has made this conversion resurrection so much fun. However, there sure is a bunch of mission creep going on!!! This is my first project to 'Just Say No', it's tough, I want the drugs... Thanks, Kurt Some of my biggest fears never happened!