No brakes on '56 cj5 - path of troubleshooting to follow?

Being a total newbie at this "Willy's Restoration World of Adventure", I'm trying to stay on track with what's important as first attention and what can wait. So far I've ID'd that my frame is fine with just a little bit of cleaning, treating and undercoating. There's lots of body rust but "pretty" comes last.

I want to thank 1948 Cal Willys Pickup for all of the tips and exchanges so far. Keep 'em comin!

Ok....Problem: When I hit the brake pedal it goes to the floor....and stays there.

Before I start blindly flailing around looking for what the problem could be, thought I'd ask here for maybe a little structure, or perhaps a sort of "path" to take getting started.

I know to check the brake fluid and bleed out the lines. Right now, it's up on jack stands all the way around and all 4 wheels are off. I took the RR drum off and had a peek inside. It was a little scary. The pads look like they are in good shape, but there's a LOT of black dust. I am going to err on the side of caution and treat this as asbestos dust. I'll double filter my shop-vac and suck out what I can, of course I'll be wearing my dust mask (can't afford a full body hazmat suit and helmet). I want to get the insides of the drums cleaned up, but first I should probably figure out why the brakes aren't working, and why the pedal just stays on the floor when depressed. The pedal will stay up if pulled up, but there's no resistance when it's heading for the floor.

I believe the system has been converted from a 6 volt to a 12 volt, since the wipers are now electric and not vacuum run. Gauges have been replaced also, and the originals appear to be disconnected.

The starter is a floor switch you depress with right foot, but key has to be turned to "on" to engage starter and turn over engine, which seems to be in very good condition running wise.

So now that I have offered up all of the irrelevant information I can, back to the original question......where should I start with figuring out the brakes, and why the pedal stays on the floor?

Check the return springs on the back of the pedals. They may have broke or simply slipped off.

Well , if it doesn't stop, there's no point in going any further...that said,.. the brakes are not the place to get cheap...I would replace the master cyl, all four wheel cyls, all flexible brake hoses, and carefully examine every inch of steel tubing for dents, kinks, and rust..it may be best to just replace all tubing...after all it's 57 years old...NAPA sells various lengths of 3/16" brake tubing...just grab a few that you think you will need, bend them carefully by hand and you're done...buy new "s" tubes for each front wheel...less than $10 each....when I got my 56 CJ home, I was shocked to find that all brake lines were copper !...new drum brakes are fine for a lightweight CJ...don't waste your money on a disc conversion...unless you plan to tailgate traffic on the interstate at 65 mph (highly unlikely)...you can buy new brake shoes and all brake hardware for not too much money...just replace everything and have no second thoughts...piece of mind is always good...I spent around $350 for everything...now this is going to be my winter project...good luck with yours.