Just how likely is it to land on a vintage, aluminum touring machine? Well ... I freely admit to being rather uninformed on this matter, but ....

From what I have been learning in the last few weeks, your best bet of snagging something vintage and of decent manufacture in this league is a Trek. Just my my 2-bits ... cuz if you get too way out and exotic, you'll likely croak before you find what you want.

Road racing machines like Alan and Vitus are not so hard to find, but they will not be a tourer. There are the Panasonics from Japan — very good frames, but same thing.

You must have your reasons ... but IMHO, the best touring frame with all the needed braise-ons would be in double, or triple-butted steel . If an aluminum bike has been crashed, a bit bent, needing a "cold set" in the stays, has a misaligned DR hanger, yer screwed — especially if you are thinking about touring with racks, panniers blah blah. You cannot / should not correct, bend, re-train, realign aluminum.

For touring, your priority is stability on a machine with relaxed angles and a longer wheelbase.

Trust me! I own a Vitus 979. I've studied this stuff a bit, and cross-examined seasoned bicycle mechanics. You are going to have to look hard, and for sure check out the product very carefully in person.

Parting comment: If I were doing even a modest descent on my 979 with touring gear strapped on somehow, I'd soil my lycra real good.