kz400 jets can anybody help?

So I am in the process of restoring a 1978 kz400b1. I disassembled the carbs today and managed to get everything cleaned up with the exception of the main jets that seem to have been wrenched on by the previous owner. These are the small threaded barrel shaped ones and seem to be rather difficult to find and not included in any rebuild kits. So all I have come up with so far is to attempt to redrill these with a numbered drill set or attempt to purchase FCR Main AirJets that according to the web seem to be about the same size. They have the same length and shape and appear to be about the right proprotion according to the pictures. So my questions are threefold and would apprectiate any imput anyone out there has.
1.)Does anyone know of anywhere these jets can be purchased. I have looked on just about everyonline site that I can come across but maybe I'm missing one.
2.) Is it possible and resonable to drill out the old mains and still expect resonable performance?
3.) Are there any structural difference between air jets and main jets that would affect the functionality asmains. They are the same length so if the diameter and treading are the same would this be a resonable swap? anybody try this before?

Any and all help would be greatly appreciated.