Well for better or worse I rigged a solution since I needed to finish my project. It turns out that 1/4" brass pipe has an O.D. of 1/2"' the same as the drain tubes I removed. Since my new transom is 1-1/4"thick, I bought a 2" piece with threaded ends. I also bought a couple of 1/4" female threaded couplings which I cut in half and then ground to about 1/4" that I used as nuts. I pushed the pipe nipples through the transom, sealed the ends with 5200 sealant and tightened the homemade nuts. Since the inside ends aren't at the low point I may have to drill holes in the nuts to allow better drainage. It's not as pretty as the original, but I will paint it all when the sealant cures and no one will be likely to notice. Problem solved....I hope.
