Is there any current launch system that could get a 75,000 kg object to geostationary orbit?
No. (Starship/Super Heavy can, of course, do anything, but it's not a current launch system.)
If not, am I correct in assuming the Saturn V could have gotten such an object there?
No.
According to the Silverbird calculator, a Saturn V could get about 60 metric tons to a geostationary transfer orbit of 185 km x 35786 km and 28º28.5º inclination, that is, an orbit with apogee at geostationary altitude but with a very low perigee.
That 60-ton payload could circularize and plane-change into equatorial GSO, requiring about 1811 m/s of ∆v. If this is done with hypergolic propellants at ~300 s specific impulse, the rocket equation tells me it would require about 28 tons of propellant, so something like 30 tons of useful payload could have been put into GSO by a Saturn V.