The Centurion was built to be 126 mm, I suspect, and I would return it to that. I run Surly New Track hubs like that on my Mercian Vincitore (120 mm spaced rear) and my '73 Raleigh Competition (126 mm spacing, hub set up with 3 mm spacers on each side between cone and locknut). BOTH bikes are kitted out with hollow axles and traditional steel q/r skewers with internal cams (Atom/Maillard), facilitating flip/flop use. Some folks will shake their heads and insist that track nuts are the only safe way to do this, forgetting that Campagnolo used to sell their track hubs with q/r sets before tracks started banning them.
The stock Surly bearings are kinda meh. I had Phil Wood bearings installed in my Mercian's rear hub and the difference is astounding.