I am looking at the GROUND UP front disc conversion for my 68 coupe. they are offering upgraded rotors and master cyl right now. Does this kit include new brake lines? I see a kit of lines that is optional for another $75. It this manditory or just an upgrade? i was thinking of redoing all the drum lines, master cyl., and wheel cyl. After pricing it, it seems like i might as well pay a little extra and go with the front disc set-up. Anything else i should replace/buy with the ground up kit?

There are a ton of suppliers offering varous disc brake conversion kits. Some have more parts than others, and naturally the prices vary. Just do your comparative shopping on line and then call one or two of the suppliers to confirm what parts are REQUIRED for the conversion, versus what parts are optional. Generally speaking I favor the kits that are the most complete. By the time I drive back and forth to the junk yard or parts store trying to find something to help save a few bucks I would rather have paid a little more to start with. All the kits should clearly spell out what is included. Check Original Parts Group. They are having a sale right now.

You can convert you're existing drum spindles. You will need to buy disc hose frame brackets, backing plates and caliper brackets. I personally prefer original GM ones, but you can get them repro now. You can buy rotors, bearings, seals, loaded calipers, brake hoses, master cylinder/power booster at NAPA. You also need the delay valve/bracket under the master cylinder, you can get that new also. You will need a new front brake line kit also.
The only thing I would make sure you used that is original GM are the spindles. I've heard there are issues with the repro spindles in regards to the ball joint tapers not being right.

You can convert you're existing drum spindles. .

To use the drum spindle the upper boss needs to be machined down .470 to use the factory disc caliper bracket. to do it on a budget you would be better off to find a used set of disc spindles and replace the consumables i.e. rotors calipers seals and bearings. if you are looking for new aftermarket parts I can get you a good deal on those if you so desire. send me a pm if you have any questions.