Nice work! I have a 1974 K4 with much the same story as yours. Guy dropped it once and parked it in 1977! It had just over 9,000 miles when I bought it. I’ve been detailing it and reusing almost every original part since day one. Whenever I do another project, if it has a nicer, original part, I use it them on the K4 and buy NOS or replica stuff for the project. Fenders, grab bar, seat and two pipes, all came from other SOHC cb750s. This way, it’s still “original” and unrestored. I also respoked the rims when I had them off for new rubber. Bike runs beautifully and is a real favourite where ever I stop! Keep up the great work.