SAK MOD SCREW Convertion. What size do purchase and where?

[bigchelis]

Hi all,
I want to Change the plastic Scales on my Victorinox 91mm with an ALOX 91mm Tinker.

I saw you just drill out the inside of the bushings and some use Hex size 6 screws.

Is there a specific place to get the correct size? Lengh I assume I would need a couple sizes to get it right. Diameter; I am pretty sure that's where I need to get exact size.

Thanks,
bigC