Bushings: my advice for your particular frame is to use the non-flanged bushings. They must be installed 5mm deep into the ends of the tube, followed by the felt seal washer and the phenolic end caps (those comprise the 5mm space and form a waterproof seal). Over the ends go the larger cupped washers to complete the correct pivot width within the frame.
Since Covid I have received several swingarms with these flanged bushings hanging halfway out of them, bent and mangled: this indicates they were too large OD. I've also received 2 arms with those bushings fully installed, but when tightening the swingarm bolt they jammed the swingarm solidly because the flanges were too thick: they must not be more than 2.00mm thick over the outside end of the swingarm, or else they will make the pivot wider than the swingarm collar, and then the frame simply jams the arm in one posiiton when the bolt is tightened. The collar is 0.002"/0.04mm longer than the distance over the assembled (bushings + felt + end caps) width. It must not be more than this or the frame will not be tensioned. This is a precision fitment.
Something else to know: there are 2 different ID sizes in the 750 swingarm where the bushings live: they are NOT all the same, yet bushing-makers presume they are (all that I have seen, anyway). This means if the bushing was made for the 1974-1978 swingarms, they will be too big for the 1969-1973 versions of the arms. Vice-versa will appear to fit, but will become loose after a few thousand miles, in my experience (I see those from time-to-time, too).
Moral of this story: ask the vendor which swingarms their bushings will fit. If they say something like "all CB750" then find another vendor: they are NOT all the same size in the 750.
And, they are shorter in the CB350F/400F arms, by 3mm. In the first-year CB350F they are shorter by 5mm for the first 2 months of those bike builds, too.
