Interesting-- I've never seen a regular tube-type PortaColor with a slide pot volume control or a rocker switch for power on/off, similar to those on the PortaColor II.
As for when it was made, the fact that it has the brightness and vert. hold controls at the bottom, but has the continuous-style UHF tuner would make me guess 1974 or '73, but the hinged handle and the style of the tuning knobs would make me guess it was a few years older than that. So, have a look-see at the date codes on the tubes, and that'll probably be about as good a clue as you're going to get.
Glad you managed to bring it back to life!
--Marty