Restoring an old CB500

[oldschoolorange]

Just like the title says I am going to be turning my friends 73 CB500 four into a Cafe racer this winter,

Any help or tips that would make this go smoother would be greatly appreciated.

I think I am going to do somthing with the suspension front and back, upgrade the brakes, put on a single seat, dragbars/clipons. Any help with what would work suspension wise would be great, as I might do something crazy like monoshock and alumnium swingarm.

My biggest problem is with the engine, it is shot, running like a bag and very little vacume on 2 cylinders. I am planning on doing a complete rebuild this winter to the engine. **** I am unable to find pistons for this bike on the aftermarket, does anyone know where I can find them?