I'd leave the auto (I assume its a trimatic?). And slowly pick up all the 4spd bits over time. If you like the auto, leave it, if you ever go to sell it having all the bits to go with it will mean its value will not be affected much at all. If you don't like the auto, then put up with it until you find all the 4spd bits. If you have all the bits it is a very easy job to change from Trimaic to 4spd.
Note the original HX clutch mechanism is an abortion of a device, and hard to find. Rest is easy.

If it is a TH box behind the original manual block then i'd get rid of it as the adapters are awful things.

Plus for the car's value to be affected by it being an auto over the original 4spd it'd have to be a pretty top $ and correct resto or an otherwise immaculate survivor car. Even if it drops in value $1000-1500 or so it'll cost you that in buying correct original bits for it unless you do it over time picking bits up at swaps etc.