"X2" means he agrees that Wilwood is a good kit.
You must determine if 9 or 10" drums. You can pull a wheel and measure the drum OD. 9" drums are 9"ID and ~10.5"OD. Look at
www.rockauto.com for parts and photos to learn more. You can also look for the "max ID" stamp on the drum, which would be something like "9.008 in D max" for 9" brakes. The spindles are different between 9" and 10" drum cars, so it does matter, and changing spindles isn't trivial.
If 9" drums, Scarebird makes an affordable bolt-on disk kit that uses Chevy and Toyota parts. For any disk kit, you will need at least 14" wheels and sometimes 15" to clear the calipers.
I don't think the much-discussed 73+ BBP disk conversion is a good option for you. It takes a skilled mechanic and raises other issues, such as changing the rear end or carry 2 spare tires.
You sure don't need rear disks. That is more of a show-off thing, and mostly for marketing in new cars today. Front brakes do 70% of the braking.
The 1969 factory K-H disk brakes are also not a good option for you, since you must change the spindles, as above. It would let you keep the SBP rear-end. A guy on FABO sells a complete setup occasionally, but ~$750 and getting future parts is hard.
Finally, I agree that 9" drums work fine. I had that with a manual MC on my 69 Dart for decades and it worked fine. Not too hard to skid the tires, which is the best you can do with any brakes. My wife drove that car for years and never complained and she is a cautious Asian lady driver. I did over-heat the brakes once on a gravel mountain road, where I had to brake too much on turns, but I also did that in my 65 Newport with its massive 11"x 3" front drums. Disks do cool off quicker, which is their main advantage, but of little concern in normal driving.
As far as the pedal sitting too high, that could be the wrong MC and push-rod, but more likely is the factory design for manual brakes. I can't say I remember from my 69 Dart. As far as "soft", that could be some air bubbles in the lines. Change the fluid (search "bleed brakes"), which you should do every 2 years unless you use DOT 5 (as I). It could also be because the factory maybe used a smaller piston in manual MC's, so you get more pressure for the same force, but more pedal travel. Check rockauto. They show a 1" MC for my 65 Dart for both manual and power. Not sure that is correct, plus 69 may be different anyway.
If you still want power brakes, which aren't needed for drums and many don't even use with disks, you can buy a new kit for ~$250 (search here) or be cheap like me and get the brackets and lever from an A-body and install a booster/MC from a newer car like the ~95 Breeze in my 65 Dart (see post). I didn't want the heavy cast-iron MC of the junkyard Dart I robbed.