Now it's coming together for you.
I don't know your model all that well myself but I can see from the photos of other similar model lathes I posted upthread that there seems to be 2 drive system options. In the first set of pics you can tell that particular model has a bench-mounted countershaft drive assembly, although you can't see much of it at all...just the a portion of the one knob if you knew what you were looking for (instead it is easier to infer it because there is no drive system visible underneath the headstock in those photos so that is effectively ruled out.).
From the 2nd photo I copied from the weblink upthread you can see the cabinet style and the resultant undermount motor and drive assembly that you know is there. In that weblink the site describes that drive situation this way:
The stand-mounted lathe sat atop a neatly-constructed, 190 lb cabinet...that held a simple but robust under-drive countershaft with its pulleys overhung on 3/4"-diameter shafts from each side of bearings contained within central plumber blocks... Strangely, although the bench model had a single V-belt drive to the headstock, the underdrive model used two - a design that can often lead to trouble when worn or unmatched belts are used. If your 12-inch underdrive suffers from a noisy headstock, vibration or a poor finish on turned work, look first at the final drive to the headstock spindle and check (by putting a chalk line across them and running the lathe) that the two belts are exactly the same length. A solution - and one that saves having to dismantle the headstock and countershaft to replace the belts - is to use a modern T-link type.
I look at your nicely organized parts photos and I see what appears to be the described under-drive assembly. If so, you have what you need but for the motor choice and cabinet. If for some reason you want to go with a topside drive system then you know where one is and what it will cost you. That price doesn't offend me...when you decide to part out a lathe sometimes the decision is driven by
the sum of the parts is worth more than the overall value of the machine itself. That's reality, and it presents a set of options for you if you were to decide on a different sized lathe or a different model altogether. Someone out there will be looking for most of your disassembled parts and you stand to get a good chunk of $ going that route if you were to so decide. I don't sponsor that (in fact I suggest it would be a shame in your situation now that we see just what all you have) but you can't ignore that potential monetization either. This is not a rare museum piece after all, and if that is your way to get you into a better suited machine faster then that may be the right call. Also consider completing this one and getting it up and running and learning on it and then flipping it on also. With the QC gearbox and those nice new looking chucks you will have some very desirable features to lure in a potential buyer. You could package up what you have now and list in here for sale online and get plenty of informed interest. That potential new buyer might want to make the call on the motor, going VFD or not, and other such decisions.
Do some more study online and you'll get lots of ideas...do some searching on the merits of VFD systems and let that research that will flow forth influence you as to motor choice. What you asked in your last post has been asked many, many times before and those searched threads will re-emerge as a study guide for your own application here. Ask yourself what you want to do with a decently large screwcutting metal lathe and also read up on how to run a lathe and all the accompanying tooling that you will need and how much space you will need for this machine in complete running form, etc., etc.
You're well on your way now and have the wind at your back it would appear. Before you mostly lies
choices, not problems that must be solved. Self-education will guide you and we are here for you as a sounding board. Keep us informed, take your time (things are moving very fast for you now at the moment), share your choices and why with us to take us along vicariously with you on the ride and ideally bring us some ultimate closure in due course if possible. Most importantly remember to
pay it back someday to someone in in a similar situation to you down the road.