Clutch issues

[66Project]

I'm building a 2wd K5, LS 5.3 with an old school 4 speed trans.
Today my 6 year and I decided with no interior, sitting on wooden boxes no windshield or hood would pull the truck out of the shop for the first time under its on power in 2 years. It was exciting other than I couldnt put it in gear.
Dual friction clutch speedway hydraulic throwout bearing and a mid 80s C10 master cylinder. The slave cylinder instructions recommended using a 3/4 inch bore MC. The factory type GM MC is only a 11/16 bore. Im using the full stroke of the MC and the pedal feels pretty good. I was hoping it would work ok but apparently it is not. So im searching the interwebb trying to find either a replace slave or a MC that would work. Wilwood obviously makes a 3/4 inch bore but its designed to be mounted 90 degrees to the firewall. The factory one is mounted at an angle and at this point I really can't change that.
Im sure someone has had this issue before so im looking for advice on an aftermarket or factory MC that is a 3/4 bore and mounts at an angle or maybe a replacement slave cylinder. Any advice would be appreciated. Thanks