at what point is it best to go with 4 wheel disc brakes as apposed to front only? I guess the obvious start would be how the car will be used... I have a '68 that will be a weekend driver, not going to the track. However, it will be a 5 speed and I plan on taking it across country.

I consider front discs a necessity. 4 wheel discs are not necessary but kinda cool.

TTFN
Mat

I consider front discs a necessity. 4 wheel discs are not necessary but kinda cool.

TTFN
Mat

+1..that's the main reason I'm getting 'em :p

Hauling ass is fun... stopping is critical. 4-Wheel Disc's may be the difference in stopping before you t-bone the idiot who pulled in front of you or not. Always error on the top end when it comes to safety...

I presume you are talking about a shift from drum to disk. Then wondering if you should go to 4 Wheel. I recently went from Drum to Power assisted front discs. I used an aftermarket kit with the two stage booster. If I had it to do again I would use the original style booster for looks.
What I found was that the discs worked fantastic and I have the same feel as my 2007 street car. The difference was amazing. My 68 now handles and feels like a new car.
What I was told was that 75% of your braking is done by the front brakes, so 4 wheel would be overkill unless you are racing.