I have a few solutions to this problem...finding a hydraulic and hydro boost pedal assembly may be expensive or time consuming (or both). You can find genuine parts from 4speedconversions as well as a lot of part numbers and which vehicle they came from.
you can also get all mechanical linkage in a kit (or individually) from USA1
I’m working with mechanical pedals that are non-hydro boost. They still need to be modified on the brakes side, but Modern Drive Lines makes a hydraulic retrofit kit to work with the mechanical pedals. This is no joke, they engineered this, not something you’ll have to modify to work in a stock setup. Call them, they will modify the kit to match your slave cylinder bore x travel and the right house fittings
73-87 Chevy C10/C20 Hydraulic Clutch Master Kit/ .750 bore / remote reservoir, Uses stock clutch pedal and rod hole (where possible) for ease of installation.
www.moderndriveline.com