K-H brake swap done, but doesnt stop!

Finally got the K-H swap and front end rebuild done today. The ONLY thing i have not changed yet is to the new disc/drum master cylinder as i still need to buy one. I couldnt resist taking it for a spin with the old drum MC. Well, it doesnt stop worth a darn! I have to literally stand on the pedal and it just comes to a slooow stop! I couldnt even lock it up in my gravel driveway doing 30 mph! I know it doesnt have the correct MC, but surely it should still have more stopping power even with that MC on it..? Any ideas?