For recoating the motor, if you have the money have all the parts powder coated by a bike specialist powder coater, that way the masking will be taken care of, then it’ll look factory brand new!
Otherwise use ordinary rattle spray cans of paint, grey primer then ordinary spray paint. Don’t worry about high temp paint etc as the engine never gets that hot. (I’ve used this meathod for years, including heavily thrashed two strokes, never had any paint peel etc) When you first fire it up it will smoke as the paint gets baked, but will look great.
Exhaust pipes/headers can be coated using pot belly stove/fireplace paint usually by a powder coaters.
Keep up the good work!