juvela

Seat tube is 26.8mm. Head tube is 25.4mm. Rear dropouts are 124.6mm spacing (Tight 126mm or 120mm spread poorly?).
I'll see if any makers marks on the adjustable cup. BB spindle marked "Cro-Mo".
(Edit: Just checked and can't read adjustable cup face due to the NDS crank blocking view but looks like a Nikyo with six small pin holes,but can't see lettering)

Very faint letters, might try rubbing with a pencil but now it looks like a - sign followed by JNG. (- J N G)

I believe that threading is JIS, as it takes what looks to be a standard bottom bracket (fixed cup soaking in Evaporust now).

When I said that the threads were fine on the crank, I can still screw in the tool but man, it won't move, it'll need heat.