Kelsey Hayes disc brake trouble

I think that will have a 1 1/32" bore and will take a bit of leg to lock em up. Get a 15/16" or 7/8" master
and you'll probably be much happier.
Also seating your pads...haul it down reasonably hard from 50 to 30 about 3 times and then 30 to to zero 3 times...they should grab a little better after seating.