front brake: rebuild or replace master cylinder?

so my stock 80 kz550a master cylinder is leaking. seems to be leaking at the plunger and the fluid reservoir. should I rebuild or replace. i also need the lever. so its pretty much just the body that is still good lol

where would I find all these parts?

if I should just replace it what is a good alternative?

Z1 Enterprises is a good first. stop Talk to their parts line to get actual real-time recommendations.