I don't have experience with the company, but looking at the kit on their web site, the parts appear to be GM factory parts. The only item not included is the proportioning valve. You've got options there. I'm not familiar with what the factory setup in 67 was for disc brakes with regard to the valve. You could go 'factory', or you could go with an aftermarket adjustable valve, like the one from Wilwood. If you go that route, you'd leave your metering block in place and install the valve downstream
from the block in your rear brake line. That's what I did on my 69 when I converted to Wilwood 4-wheel disc brakes. I located the valve about halfway down the driver's side frame rail, tucked up inside it, spliced into the line. To do the job yourself you'll need tools to make double inverted flares on tubing and the associated fittings. I highly recommend practicing on pieces of scrap tubing first until you're sure you can get them right. You just get one chance on your brake line. If you get it "too short" you'll wind up having to replace the line, and getting to the section that goes up and over the rear frame crossmember usually requires separating the body from the frame a little bit to get clearance.