hi, I have a 29K15, complete with original treadle table, and like you, I made a flatbed table for it. These tables were a standard Singer accessory, and originals are very rare to come by.
Have to admit, I love my 29K. Have you come to terms with the tension ok? They are quite tempramental, but worth the effort for the quality of stitch, and the pure fun of using such a machine.