Curtis Novak makes a reissue bass humbucker, if you just want to swap the pickups and keep your 73. He also makes a reissue Bisonic but he can probably make either one sound how you want it to sound. if you go that route, it may be easier/of more value later, to sell the package with what at least looks like his Bisonics to the eye...and be sure to hang onto the original Humbuckers. Also Curtis can maybe mod your stock Humbuckers, not sure about that. You can do alot with the 70s bucker though, in my opinion, if you play with the amp. At some point I suppose though, If you are performing live and really loud, it could be limiting. Also you are welcome to check out my 98 sometime, if you are that curious. the biggest difference is the depth of the body, about a quarter inch:
And the pickup is a little more contained like I said. the same tone, but tighter on the 98, than the 70s. just shoot me a message if you want to check it out.