Stripped thread for BB cable guide

I was just about to mount a new plastic cable guide under the BB on the 90's Colnago Master Olympic I'm currently restoring and noticed the thread was completely stripped. There was pretty much a smooth round hole. I was thinking maybe getting a thread tap and make an M6 thread instead of the original M5 and just get a larger bolt, but then I thought a more elegant solution might just be to get an older style clamp-on cable guide, such as this:

Any thoughts? What would you suggest?

bolt with a nut?

Yeah, I thought about that as well, but I would prefer to not have to remove the bottom bracket again if not absolutely necessary.

The stop for the rear mech cable will be under the chainstay and you will need to go under the BB for it to line up. Dab of Tiger Seal or similar to keep it in place?

It's actually on the outside, but you're right, the cable might end up touching the chainstay, plus the old Campag clamp-on cable guide only seem to work with 28.6 mm tubes, and the Master Olympic has a 32 mm downtube.

I just placed an order for a threading set. Using an adhesive or similar would probably work, but my OCD would be forever nagging me about it.

A 5mm plastic expanding rivet would do the job too. Can pick them up for next to nothing in car accessory shops.

Thanks, that will be my backup solution.

Something like these would be easier, just push in, no screw, no glues. A simpler solution:

https://www.ebay.co.uk/itm/Peugeot-Bott ... SwcqxfZjlz

https://www.ebay.co.uk/itm/RETRO-BOTTOM ... SwubRfOA-3

https://www.ebay.co.uk/itm/Road-bike-MT ... Sw5EdfLpSf

The expanding rivet or press in/click in guides are fairly standard now.
it's what i have on both my mid 90's bikes

Also allows any water that gets in, to get out again.
A thread doesn't really do that very well.