I got all 4 retractors out yesterday and searching for the best way to go fix'n them up. 

Only 4 busted bolts. Seats are gross.

The budget can handle pretty much anything as far as this goes. 

Looking at:

Snake-Oyl

Andover restraints

Seatbelts plus

Corvette Seat Belts and Classics

Some offer rebuilds of originals. some offer outright new items. 

I'm leaning in the direction of refurbish my set, I would like to go original, but don't need show quality.   

I was very happy with the shoulder belts that SnaakeOyl made for me - along with NCRS-qualifying labels. But it was a big expense and took much longer to get than I had planned. In the end, still happy with the belts, but just know what you're getting yourself in to as far as fabrication time and cost. Good luck!

I also used Ssnake-Oyl to restore all belts on my 1980.  They still look great today.  Cost is a bit more, time was not an issue when I had them restored, but I don't recall it being excessive. The webbing was in bad shape, but that was all replaced and came out like new.