I just got a 1973 too
I just picked up a 1973 LWB R75/5, fairly well taken care of but still needs some care. I don't plan on ANY "pretty" work, just make the mechanicals near perfect. Clean and re-grease the steering head bearings, service the wheel bearings (just did that on a 37,000 mile /6 and found them to be totally dry, so a god idea to service) I might replace the coils with a green coil form Motorrad Electrick and new plug wires (would that be an up-grade from 40 year old stuff), then pull tranny and service the splines plus check out any rear main seal leaks, then as long as the swing arm is off I will pull the bearings and freshen up the 40 year old hardened grease and that means you have to replace the $6.00 seals. That pretty much makes for a reliable runner. Of course adjust the valves, ALL fluid changes and new crush washers. That will give you a bike to ride to most rallies and events and get you back home. I plan on running my /5 to the Salem Rally this summer, she looks like a 1973 bike (Craig Vetter fairing and an 8 Track player) but mechanically she will be a solid runner. Oh, one more thing I will be doing is replacing the positive starter wire, starter to battery, a new wire should reduce the volts required to start her up and I also sent off the starter to Motorrad Electrick for a rebuilt. Opps, another item(s) I replaces is the starter relay $10 and the voltage regulator, I think about $27. The idea there was to get rid of 40 year old electrics. My main goal is to have a very reliable runner that still looks like it did in the 70's. Not a restoration, more of a restro-rection, yeah, that sounds good. Very much unlike it operator...
Have fun getting her ready.