Basically any injected Chev SB will net you a useable distributor. (within reason of course)
I don't believe on a truck there is any problem running either the "big cap" or "small cap" distributor with TBI, so a distributor off of say a 1986 TPI camaro could be a donor. So would a TBI camaro.
Somehow apparently you can make the 1981-1990 CCC car/truck distributors work I am told, but I'm not up on that.