The yoke is a little marginal by modern standards for 3000 psi service. It's not to say it won't hold up, just that there is no guarentee it will hold up. Fairly thin yokes were originally used by nearly all manufactures when 1800-2475 psi tanks were common. They got beefed up slightly for 3000 psi service but then, industry wide, they got a lot heavier in the mid to late 70's.
A 2250 psi steel 72 would be a better way to go with an older yoke.
The actual condition of the regulator will depend almost entirely on the conditions in which it was stored. I would suggest getting the reg serviced or at least inspected before you use it.
The first and second stages tend to be very durable and age well and the seats may still be in great shape. But the mushroom valves in the mouthpiece have a tendency to get really crispy. You can dive with bad mushroom valves, but it increases the amount of water that will flood the hoses and make clearing water from the reg much more difficult. The butterfly exhaust valve is just the opposite, it will tend to get very soft and gooey and generally disintegrate.
The hoses also need to be scrutinized carefully. I have seen generally good appearing hoses that due to age just won't take a lot of stress and are very prone to fail, particularly at the point where they attach to the regulator body.
