FXRS wide glide swap

I have just purchased a Spyke 63mm Wide Glide front end for a swap on my FXRS(narrowglide) I know everything will bolt up but here is my question. I have a billit 21' wheel that is unfortuneately narrowglide also. I have seen these rotor spacer kits which advertise the ability to use a narrow glide wheel on a wide glide front end, but are the axles all the same? will The axle that comes with the spyke front end work with a narrow glide wheel? or do I have to pray that the axle with the rotor spacer will work with the front end? Any help is appreciated

[frisco-rigid]

Good question bud
I just measured a couple axels and found this-----
The bearing surfaces on the wide-glide axel are C-C 6" and 7.5" over-all..

The bearing surfaces on the narrow-glide axel are 3.5" C-C and 5" over-all..

If the the bearing surfaces on the axel sent match up to the narrow-glide wheel bearings you're cool, if not you must get the correct axel.. If the new front end is specifically to allow the use of a narrow-glide wheel then I would suppose the axel is ground that way,, perhaps with a continuous/un-broken bearing surface..
Another possibility,, does your billet wheel have re-moveable hubs thus allowing the re-placement to longer wide-glide hubs..? Some manufacturers like PM have them, perhaps your wheel is made that way too..

As far as I know the rotor spacer kits only space the rotors..