There are a number of records of his available. I have one called "The Mac Wiseman Story" which was recorded in 1976, and has a good selection of his tunes. I think the old selections have also been compiled. I first heard him on a collection of "20 Country Waltzes" including "Waltz Across Texas" (the Ernest Tubbs song) and "The Last Letter". This too is available. I have no idea what of the duet/bluegrass albums are around.
yours, Peter T.