New brakes

I believe that as long as the master cylinder is 1967+ you should be all set.

You may need to upgrade the brake lines to the front to a stronger line quality (braided Stainless steel lines???) The calipers require LESS pressure than drum, and if you still have drum in the rear, you will still have to apply enough pressure to stop the rear... With old/stock lines in the front, the PSI will be increased from lower psi required, so its possible you will blow the front lines...
I'll try to create an example.

{ O = fluid PSI required }

Drum Drum
Front Rear

OOOO . . . . . . . . . . . .OOOOOO
|--------================|
OOOO . . []. . . . . . . . .OOOOOO

{master cylinder}



{ O = fluid PSI required }

Disk Drum
Front Rear

OO . . . . . . . . . . . .OOOOOO
|------===============|
OO . . []. . . . . . . . .OOOOOO

{master cylinder}

Older cars have more fluid to the Drive wheels to stop the power from going to the wheels, where as more modern cars have the front as the primary braking to provide a more stable/predictable brake... If you look at a master cylinder on a newer car, the front lines have a bigger bore/lines to provide the majority of the stopping force to the front, and a smaller bore/lines to the rear. When ours were made, they were either about equal all the way around or setup for the primary stopping at the rear as that is where the power comes from. (thats why in the diagram I made the rear lines like ==== vs ----, to show where the majority of the fluid goes)

Don't get me wrong, the disk are great, but you will lock up the front while the rear is still spinning if you just hit the brakes without expecting it. The front end is light enough there isn't really enough down force to keep the wheels solid on the road, so when you step on the brakes, yes they will work - too well. the front may lock up stopping and the front will just skid while you apply more pressure to stop the rear.

My suggestion would be to also get the rear converted over as soon as you can WITH the parking brake setup (there are cheaper rear setups w/o parking brake(e-brake) but you will be glad that you still have it), then you will have the stopping ability you expect, with a lot less worry and effort trying to stop.

I currently have disk in rear and drum in front with new lines all the way around... why? so the rear is the primary stopping as there is the down force needed to stop, and drums in front to keep weight up front to keep the wheels from skidding. Yes I have locked up and skidded with this setup as well just from trying to see what a 75-0 would be like, but I had a safe place to try the handling out, and see what different speeds and stopping conditions (wet is still SCARY) are like. I have had a lot of problems with brakes in the past, and from trial and error, and what others passed on to me, I am trying to give you the best info I can.

Don't let this scare you, I wrote this to give you a heads up as to what might happen and ask you to PLEASE take it easy and get use to how this setup feels so you know your car. If it does actup, or not what you are looking for, go over the lines, look into rear disk, and talk to the older guys at the auto parts store... they have more info from Experience than the younger crowd.

Thanks very much guys I'll keep all that in mind... good idea finding a spot to try then out to get to know them...

Get the book "Brake Handbook" by Fred Puhn. It explains brake systems very well. Disc brakes actually use more line pressure than drums since drum brake are self energizing. When you use drum brakes the front shoe pushes the rear one against the drum adding to the braking affect. Most brake systems that have discs and drums have the discs on the front. The master cylinder should be designed for that as discs use less fluid than drums do. The size of the line doesn't matter, the same amount of fluid is moved regardless of the line size. When you have a disc/drum combination with the drums on the rear you need a metering valve so that the pressure is applied first at the rear to overcome the springs on the shoes before pressure is applied at the front where there is no spring pressure to deal with. Then there should be a proportioning valve to regulate how much the front brakes are applied compared to the rear. The fronts will do most of the braking due to weight transfer. As you apply more braking effort the weight transfer increases so you need the rear line pressure to go up at a lesser rate than at the front. You always want the front brakes to lock up before the rear does. All of this is explained in detail in the book. It is just a matter of using the right combination of parts and properly adjusting the proportioning valve.

A little bit but there is still weight transfer that will load the front wheels.  It will depend somewhat on what the static weight balance is. This is why an adjustable proportioning valve is important.  You need to be able to make adjustments to allow for the weight balance of the vehicle.