Same exact pump I have. Bought mine new in 87-88. The date is on the bottom of the foot. Made from Columbus tubing. I did new gauge hose and internals on mine. Works perfect.
I was guessing a similar age on this one. I found one online that was labeled as a '79 (with a picture of the date stamp) and this one is notably newer. can't find a date stamp, though, even on the bottom of the foot. Would you mind taking a pic or two that shows its location? This pump was definitely used, as the bottom of the foot has the paint well worn, but it doesn't look SO heavily worn that any forged date marks should be also worn off.
The piston gasket in those is made of leather, so it's usually just that they are dry, not non-functional. Pull it, and slather with whatever grease you have handy...it'll give you a chance to evaluate the check-valve, at any rate.
If the handle is held on with a large thread, just buy a coupling nut of the appropriate size, and epoxy/glue it to your handle of choice.
That's what I was going to do for a handle. But I didn't want it to be a total hack job, either, so I was planning to get a nice piece of somewhat large diameter hardwood dowel, sand it down a bit into a smooth shape, stain and seal it, and then use the coupling nut method you described. Might even drill it a bit to recess the nut into the new handle.
I get that I might be able to revive the old seal, and I might do that so I can evaluate the gauge. The gauge does have screws on the bottom that I think I've read can be used to zero it out, if it works. But a brand new one is only $11 from Silca, and supposedly the new ones are a touch thicker and more durable than the old ones. I absolutely have to buy new rubber, anyway. I suppose I could strip it down today to check it out. I was going to wait until I was back from my vacation so I could keep track of the parts, but I could just do the plunger to check the leather washer and evaluate the gauge.
*edit - FWIW, I pulled the plunger to check out the leather. It's still there and mostly intact, though a bit crumbly. I put a bit of Phil Wood Tenacious Oil on it and reinstalled to check the gauge. The gauge seems good, so I'll leave that and just replace the rubber and the leather. It has a hard bottom out "clunk" when pumping, and I'm wondering if there's supposed to be some sort of rubber bumper down there.
At any rate, I'm tempted to do a little bit of updating to this pump, too. The existing rubber hose is a bit on the short side and tends to flop all over the place. It's a bit of a PITA to manage when I want to set the pump off to the side. I'm sure that's partly because the 2nd hose keeper on the handle is gone. But I'm thinking about putting a new, longer hose on it so I can manage the hose better.
I also might put on a new pump head eventually. I have a newer silca-style presta head that came with my prestaflator and I put that in my toolbox more or less permanently because I got tired of whacking my knuckles on the cassette or the brake disc when removing it. I ended up getting a silca (new) "crack pipe" disc-wheel presta head for that. I've also had my eye on the Hiro chuck. If I put one of
these onto the hose, I'd be able to use my current "crackpipe" head and add a Hiro head later. It's also tempting to buy a few of these so I can make all my pumps compatible with the same presta chucks. The prestaflator more or less already has one on it (albeit a much cheaper version).
