The original RCMB got absorbed into one of the other magazines, probably Model Boats eventually. With the various company buy-outs and mergers and commercial swaps that have happened over the years, I feel that this particular plan may have slipped away, but there is a good selection of plans originally commisioned for magazines at http://www.model-dockyard.com/acatal...zine-Tugs.html Mostly of more recent ones. "More recent" in this case means "within living memory"..
If you like the look of yours, there is no reason why, using modern gear, and a bit of research and perseverance, you should not end up with a good working model to be proud of. Unique, as well.