Union Lockstitch Machine Sewing

Despite worn out parts and its age, my Union Lockstitch machine is still capable of sewing 3/4" of belt leather with #277 thread, top and bottom. Once I replace the needle bar with a new old one and get the proper needle set screw, and obtain #3 needles and #4 awls, I expect to be sewing with #346 bonded nylon thread through the same thickness.