Ross,

You now have the makings of a machine that will give you a lifetime of use. Forget about getting it back to original, there is very little intrinsic value in doing so, just concentrate on getting the best lathe you can out of the two.

All you really need to worry about at this stage are the centre heights of the head and tailstock. Choose which is the better of the two matched pairs, say one has a plain head and one has a roller, go for the roller, if they are both roller heads, go for the one which is the smoothest. If they have been left for any length of time in a pre loaded state, they will be very 'ratchety'. A new pair of bearings will require a remortgage of your house, unless you are lucky as I was, and got a friend to regrind the special outside races for me.
Clean off the new old bed with scotchbright and oil, that should clean things up rather well. Measure it up around the high wear areas, normally from the chuck mount to about 6" towards the tailstock, a thou or two should be OK, anything over that and you really need to get the top refaced. Only then see how the matched pair fit to the bed. you might have to do a little realigning of the head and tailstock, a fairly easy job, Once you have that done, concentrate on the saddle, leadscrew and gear areas.

Once you have the bits on the machine you want, and they are running together well, then start to rob the leftover pieces for better looking or replacement parts.

Once that stage is reached, you can start to get it fine tuned and modded to make it an exceptional lathe.

It looks like you have got all the attachments you will ever need, especially the rocking horse travelling steady, and the toolpost grinder, if it is any good. If I was you, I would empty the wooden box all the bits came in, and put it on a sheet of plastic (a bin bag), line it out with newspaper, put all the siezed and rusty bits into it (not electric motors), then dribble over the whole lot with some cheap engine oil, put newspapers over the top of that and pour some oil onto that as well. After a week in there, the parts should be ready to clean off and work on.

John