Rear drum to disc conversion question, Do I need to do anything with the master cylinder? Options

[GriffGirl]

Someone told me he thought I will need to do something with/replace my master cylinder when I convert my rear drum brakes to disc brakes; something about the proportioning valve.

Here's what he said:

In regard to your brake swap, I could be wrong, but I'm almost positive that you'll need a different proportioning valve...When you do it, though, you should see about swapping the proportioning valve and
master cylinder (if it's different on the GTs)... Drum brake wheel cylinders and disc brake calipers use different amounts of fluid (typically) and if you swap from the former to the latter, your rear discs brakes won't be doing as much work as they should.

This is all greek to me. Help? Is this something I should look further in to?

[GriffGirl]

^I have all of that stuff you listed. It was the proportioning valve that came into question; it's my understanding that it is not something that is required for the conversion, but if swapped, will increase braking efficiency. I just wanna make sure I'm thorough and cover the details. I'm kinda OCD like that.

What may happen is if I don't find a p-valve by the time I do the swap, I'll do the swap w/out it, and swap out the p-valve at another time when I do find it. If it goes that way, it'll be interesting to see if there is any difference in braking efficiency.