The sway bar mounts are the same as with the 60s, our bar went back on OK, with exception of having to space it back 3/8" to clear the rear cover because of the larger ring gear. Our bar had been made to fit very close to the 60s so not surprising.
Govlock sourcing is really tough, as GM will not sell new ones except parts for a specific vehicle by VIN. I tried to get one several times from them without success. They do sell parts, apparently to some of the rebuilders, as they do have some of them rebuilt, but as you have found very expensive.
Personally, I would get a used 70s with a Govlock and put a gear set in it before I would put $600 into a 60s. Pretty much everything you have will work with the 70s except for the rotors, which have to be a different ID by a little bit. All the rest of the brake parts bolt right up, as do shocks, springs, etc.
You might even get a bit better stability with a new axle. Our 60s had over 1* of thrust angle, and the 70s came it at zero thrust, which I have never seen before in a live axle.
Govlock sourcing is really tough, as GM will not sell new ones except parts for a specific vehicle by VIN. I tried to get one several times from them without success. They do sell parts, apparently to some of the rebuilders, as they do have some of them rebuilt, but as you have found very expensive.
Personally, I would get a used 70s with a Govlock and put a gear set in it before I would put $600 into a 60s. Pretty much everything you have will work with the 70s except for the rotors, which have to be a different ID by a little bit. All the rest of the brake parts bolt right up, as do shocks, springs, etc.
You might even get a bit better stability with a new axle. Our 60s had over 1* of thrust angle, and the 70s came it at zero thrust, which I have never seen before in a live axle.