As a retro grouch user of square taper still I am...
But I recall this being discussed some time ago. Can't find the thread right now.
We'll indulge your every wish.....
Way back there must have been a Campa Super Record BB with accompanying crank that had a hollow (maybe not hollow) Ti axle, cup and cone steel bearings, right?
Now imagine that ISO BB with cup and cone Cult bearings running on Krytox loaded oil and a Record carbon crank.
Impossible I hear you say?
No, you can build your own relatively easy.
The bearings would be the same as the CULT bearings used in the top end of Campa's wheels. It's simply conform to a plain vanilla 6903 standard size bearing.
Pick a high quality Ti axle, BSA or ITA alloy cups of your choice and you're done. Easy peasy.
No need for seals, you're going to flush these bearings clean and relube them whenever you think you should (probably quite often) and ride happily ever after.
That's the kind of BB a car company such as Alfa Romeo would have offered before they scrapped the car that's going to be replaced by the next model. That was Europe in the Seventies, young man.
Estimated weight for the BB ? I'd say 140g with room for tweaking.