Fred, two things weigh heavy here. You either have to keep your car stock or not. There is no inbetween.
Having said that, I have converted both of my Ford Classics ('55 Customline & 59 Galaxie) to power disk brakes.
Power disk brakes will put you through the windshield, they don't pull to the side, they dry out fast and they don't fade. If you drive your '55 in today's traffic I highly recommend you install disk brakes.
Here's the deal (you're in for a treat)... The 1955 Thunderbird and the '55 full-size Ford Cars used the exact same spindles. Here are the Ford Parts Catalog part numbers for 1955 spindles. S=Thunderbird and A=all other Ford cars:
You can use a Granada spindle to take the place of your originals. That means you can put your original spindles in storage in case you ever want to revert back (I guarantee you won't ever go back).
The Granada/Lincoln Versailes setup bolts right on to your original ball joints and the set should include the spindles, calipers, rotors, and backplate (wind catcher). If your wheels are 15", you can probably use the originals. If they are 14", you need Granada-type wheels which are designed to give clearance for the calipers. Several steel wheels fit.
If you are serious about this retrofit, let me know and I will go into more detail. - Dave