GENTLY rub the paint off, and find a 3/4 HP "Century Electric" motor. It may be a "geared head"- single speed, if not multiple.
Century, Lima, and Master brands, commonly with 1 fixed, else 2, 3, or even 4 selectable ratio integral gearboxes dominated small mills - all makes - in the days before DC Drives or VFD.
IIRC, Century & Lima merged, may later have been acquired by Master, which survives as part of ABB's Baldor-Reliance division, yet today.
AFAIK, the multi-speed type of motor in the 1/2 HP to 2 or 3 HP sizes small mills needed hasn't been made, new for several decades, though.
The cost of 'many' gears, long-serving low-hassle lube supply, and shifter mechanism simply became far too costly to produce vs a VFD+3-P motor, ELSE DC Drive+DC Motor.
They are also inordinately HEAVY bastids, so do have a care if you go to remove it as part of your overall refurb.
PS: Now that you have it unblocked, check your spindle bore against common 5C collets.
Hardinge had the bad, but 'handy', habit of using 5C for 'native' spindles on mills and lathes, even had some castings in early years that could be EITHER a horizontal mill spindle mount OR a lathe headstock.
I say 'bad' because a #7 B&S, or better-yet, #9 B&S taper had way to Hell and gone better grip, most especially if a milling cutter had serous pounding to do.
Absent hammering loads, a 5C is similar in grip to an R-8, neither of them quite a match for the #7 B&S.
OTOH, as said "handy" because 5C collets, round, square, hex, etc. are about as common as housefly poop, and not greatly more costly.
You'll have a far more nicely made mill than a crude, rude, and socially unacceptable Burke #4 El Cheapo, but the Burke had a #9 B&S spindle, could be had with up to 3 HP, and even at 1 HP would eat HALF the Hardinge mill's lunch.
I say 'half' because the silly Burke only had half the table size, half the travel, and half or LESS the Tee slots (ONE only, would you believe?)!