[dsraven]

yep, that's why they call it hot rodding, because a lot of what is done isn't word for word out of the instruction manual put together by someone who has never seen the end result. mostly it's because there is no off the shelf part made for the purpose. it is also because the price tag for those parts, if available, prohibits the purchase so guys just build what they need from parts off other vehicles they already have or can get cheap.
if I were you I would fab something up that works. cheaper, probably gonna be stronger and you get what you need. personally I would use a hydroboost just for it's smaller size and no need for a vac line to run way down there. that's just me though. there would be hydraulic lines but they could be steel for the most pat, with flexible parts on each end
leave the pedals and clutch linkage where they are, connected (clutch) with the brake pedal held at the top of it's stroke. get rid of the master cylinder and clean up the area of rust, dirt, grease etc. then get a booster and master that is gonna work for your brake system, then fab some brackets that will hold everything where you need it and still work for the clutch linkage. ensure the clutch linkage can do a full stroke plus some extra room for working on it. maybe use a booster mounting bracket you can purchase separately or buy the whole booster/master/prop valve assembly built for the automatic trans version of your truck and simply modify it to be further down the frame? I think I seen one set up where the builder simply used the original master cylinder, gutted and drilled through, as a guide for the pushrod to run through and then mounted the aftermarket booster/master behind that down the frame a way. it may not be spaced far enough out from the frame though, not sure.
anyway, where there is a will there is a way, you can figure it out.
what my dear old granny used to tell me.