There are many quality 80s japanese touring frames, that cresta looked like the better deal as t700 is a bit high for just frame in fair shape. Having said that picked up a stock 85 t700 (entire bike) and must say it is a very high quality bike as specced and very impresssed by build--it was well worth the 450 spent fwiw, you can probably find something similar for that price if you are patient. The TB frame is noticeably lighter than other tourers from that age, at least to my casual hefting. Triple water bottles brazing is preferred, eyelets are a must but singles should mount fine with tubus rack for fenders or go for double eyelets as well, long wheelbase of course, many can be converted to bar end shifters, etc, front fork bosses are nice, cantilever brakes are peferred. the t700 had 40h rears and 36 fronts, 40h rear are desirable if you can find them even if in 27in, at least for me.

Biggest thing is cost to build up frame, you can probably find a better deal on a whole bike and part off what you do not need unless you already have parts. I looked for some time for a quality tourer in good shape and can tell you missed out on some 500+- deals (93 trek 520, mid 80s centurion pro tour) because I was being too cheap, but as noted above in the end that is about what I paid and is fmv for ebay sourced golden age tourers in original condition--whole bikes. Frames will be cheaper obviously.