@Junky I have a late '80s/early '90s Paco panto'd frame with TSX tubing. "PACO" may the actual builder's name and not a reference to any previous racer, but that is pure supposition as I have no evidence to confirm that hypothesis. I also cannot confirm that "PACO" existed as an actual brand other than the very few (now 3) branded frames I have seen, including mine though I am sure there are many more. It is possible that they were contract built (by an artisan builder or large scale operation, i.e. Vetta, Billato, etc.) for a small shop of that name, or they were bespoke frames custom made for racers living in the area of the builder. My frame has a racer's name on it, but I have been unable to trace the name and I have no idea at what level he competed though I assume given the high-end level and cost of the frame when new that it was raced well above entry level competitions.
Given the size of your frame I would assume it to be Columbus "SL" or "SLX" (usually taking a 27.2mm seat post; is there any tubing decal remnant? Oria tubing was also commonly used); but it could easily be a "Tretubi" type frame, or mix of tube types depending on its model and price point. I still think it would be a full "SL" frame at minimum. I would place it about mid '80s so it could easily have "SLX" tubing, and that can be verififled with the BB assy removed and looking/feeling for the helical ridges in the down and seat tubes. "SL"/"SLX"/"TSX" fork steerers all had helical reinforcement ridges (5 total "ribs"; see photo). My frame has a vented Silva BB shell, not the Cinelli.
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