It would depend on the disc conversion kit you buy. But I would think most any shop would be able to mount the kit. It would depend on how complete the kit is. Most of the kits i've ran across seem to be aimed at the average do it your selfier.

I used the disc conversion kit from Classic Preformance on my 67 el camino and it was as simple as unbolting the old spindles and brake booster and bolting the new ones on. The only problem I ran into was tracking down the fitting to make the stock rear line fit the new proportioning valve. The hardest part was bleeding the brakes when I was done.