Not sure what TTS stands for, but 121 is the width (length) of the spindle, which you've confirmed with your measurements.
A mm or so either side of that should be fine, but I think the Sugino will be too wide at 124.5mm
It also has a JIS (Japanese Industrial Standard) taper, rather than ISO. Far Eastern kit is normally JIS and European ISO. Assuming your cranks are original, then they will have an ISO taper. Velosolo's FAQ
has more info.
In short, what you're looking for is a 121mm English threaded BB with a square, ISO taper for a road double chainset (assuming it is a double and not triple).
As a double is pretty much the norm, retailers will state if it's for a triple or single (often called pista or track), so assume double unless otherwise stated.
I think you'll struggle to find a new BB in 121mm: it's a lot longer than any of the current kit, so you'll need to scour Ebay, Hilary Stone
and forum ads (try posting in Wanted).
But like I said: what's wrong with yours, I have one that may do the job.