What if I don't change my Master Cylinder on a disc conversion?

It takes more fluid to fill/move the caliper in the discs than it does for the drums. You need a larger reservoir or the front one will run dry.

If you want to take a chance of your brakes not working, it's your call. The possible consequences are you can crash and get injured up to and including death. It's not worth the risk to wreck your car or hurt yourself and/or others. If you want to save money on your build, do it somewhere else, not the brakes....

I say get the proper master cylinder and prop valve for your application. I would not put my son's life at risk by trying to save money on brakes or recommend someone to do that to their kid. It just cost $12,000 to bury my mom a few months back, you can buy alot of master cylinders for that.....