I have had the same problem tracking down suitable cruiser workers. Toy Specialists in Mesa AZ on Broadway and Mesa ave have done alot of yota stuff, but I don't think I would look to them for a sbc conversion (maybe just me). The conversion isn't too hard once you have the conversion parts. I would trust 4 wheel supply in downtown phoenix to do the actual work if you supplied all the required parts. They are located on Washington street and around 44th street, next to sky harbor airport, They do alot of fabrication there. HTH
I would give Tim Hill in Marana area a call. He's trying to do less and less mechanical work but he'd probably know who does good work in the area. He'll talk cruisers with you for hours! Great guy as well.