Holes for brake mount is opposite

There are a couple models of brake caliper that don’t require a spring retention hole on the frame:

Paul Motolite & Minimoto

Avid Shorty Ultimate

Dia-Compe 988 (model number might be incorrect. There have been a few models that use the outboard spring hole and possible the 988 doesn’t use a spring hole at all)

I’m sure someone will chime in with some other options.

I assume it’s a Centurion Pro Tour 15 touring bike but I can’t tell from what little information you posted.

If the bike is a Pro 15, then frame’s probably intended for use with traditional cantilevers and probably came with Dia-Compes. There is a chance the frame was built for brazed on Gran Compe center pulls, as Centurion imported Pro Tour 15 bikes with these brakes, but I never seen that bike in person or even seen pictures the bosses for the Gran Compes of this era. However, I believe that these brazed on centerpull bosses differ slightly in placement and design from brazed on cantilever bosses. (I know the brazed on centerpull bosses I have on my 650b bike are in the wrong position for cantilevers.)

If the bike’s a Centurion, then it also more likely from before 1990, as the company that owned the Centurion brand, Western States Imports (WSI), stopped selling bikes un the Centurion brand in 1990 and consolidated everything under its DiamondBack brand.