Apparently RB used an AIWA TP-1011 tape machine preamp to boost his signal. Fortunately, the good folks at FSB were right on it (as usual). Here's the thread, complete with vero layout!
http://www.freestompboxes.org/viewtopic.php?f=28&t=13891&hilit=tp+1011&start=40Read the whole thread. It seems there were various mods proposed as this project developed.