I rode on a pair of the same ofmega hubs on my touring bike from SFO to Atlanta. A few months later I found out that the Italian grease that came in those hubs turned into a crayon like muck, and mine were close to toast. The axle thread in the rear is likely the same 10 x 26 threads per inch that Campagnolo and Joy tech has traditionally used. Believe it or not, one inexpensive solution is to replace with Joy Tech, they use the 10 x 26 tpi, or if not, their whole axlesets tend to inexpensive. The rear ones are engineered for 1/4 inch bearings, you should be concerned with o.d., as far as cone/ dustcap clearance.
I cannot tell you much about the front one, but it might be possible to look up on line Sheldon Brown possibly.