Originally Posted by squirtdad

Replacing the bottom bracket will not change the italian threading. the unthreading may be less of an issue with a cartridge..but you will need the right tools to install the cartridge

Lot's of people (me included) have italian bb and don't have a problem with unthreading

The simplest option might be finding some one or a shop with the right tool or buying one....they are like $18 to $20 https://www.benscycle.com/p-3064-par...Fabm7Aod-z4AWA

the ofmega bottom bracket for a cometizione is asymmetrical with iso taper.

my previous research is that the only option for an exact fitment replacement cartridge is going to be a Phil Wood which is expensive

any option i found with a iso taper (like the miche for used for track and fixie bikes) did not have the length on the right to provide proper clearance and chainline.

I chose not to deal with the Iso crank on a JIS taper as I am a big guy and put some a fair amount of pressure on the crank.

If I recall right using an iso on a jis move the crank out 4mm (check sheldon brown) so if you are ok with the not fully seated crank then a 70/115 with jis taper would be about right.

have fun