welcome to the 'bolt Dave-by-the-way! if the 56 has a 6cyl, it's the much loved [by some] 235 - in 56 they did have a 265, but it was the 'new' V8 - the 'power brake' bit is a vacumm brake booster called a HydroVac, the master cylinder is actually the wimpy little part under the floor at your feet, at least if it hasn't been modified
the power steering and AC are possibilities, as modern aftermarket additions that would require some creativity on your part, but w/ the 235 in a big truck you might be a bit underpowered - my advice would be to get it workin as good as it can in the original configuration, drive it for a while and get a feel for what the truck can do
the folks here would love to see some pics of the big boy - maybe you could send some pics for the gallery
Bill
