I dont know of any complete kits but If you plan to keep this vehicle long term and really enjoy and drive it and you don't mind putting a few dollars into it....
Purchase a serpentine belt system off a 89-91 Sub. Should be $50-100 at junkyard, Craigslist, etc. I paid $80 for a nice running one. I invested another $200 for powdercoat, new alt, power steering pump, ac delete idler, belts, tensioner, etc. None of that was really necessary but I wanted it looking brand new and reliable. This same set-up is over $1000 through GM and I have less than $300 into ours.
PS box are easy to find new and used but I'd suggest upgrading to a CPP or Borgeson for $350-500 and quickening up the ratio to more modern feel.
Definitely check the frame for cracks where box mounts and add a brace from ORD, Autopower. Etc.
Borgeson steering shaft is nice upgrade.
PS lines are easy to find but I had mine custom made for $150 as I added a hydroboost brake booster as well.
So less than $1000 for a reliable modern set-up.
Again, I think if you searched, you could probably buy all used for $200 for a v belt system and box. I actually think I have a complete v belt system other than the crank pulley that I'd give away if you were close.
