No, Powersteering assist braking is kinda like vacuum assisted, but instead, the hydraulic "boost" is provided by the power steering pump. eh, apparently not used in yours.
If you just have a normal master cylinder and some brake lines coming out, more than likely you could convert over.
You would need a matched set. ie, master cylinder, and booster to go with it. Modify some brake lines, and connect a vacuum line from the intake somewhere to the booster.
If you don't mind used, you could get away with spending a few dollars at the junkyard. Maybe $50-$75??
Hope this answers your question.
1997 Pontiac Bonneville SEi-SCRAPYARD
2000 Chevrolet Blazer LT 4X4 4.3L
2002 Chevrolet *-10 LS Ext Cab 4X4 5.7 V8