All the factory mounting points are there on the front subframe and lower A-arms, even if the car did not come with a bar. Restoration suppliers can provide stock parts, the aftermarket suspension kit suppliers usually will have some sort of stiffer than stock improved handling type kits too.
Since the '68-74 Nova front subframe and suspension is the same as '67-69 Camaro/Firebird, there are a ton of replacement and aftermarket kit options....here is one off just a quick easy Ebay search.:
This is a 1" bar, it will be a little stiffer than a stock bar which was 13/16" IIRC.
Includes the install components: polyurethane black bushings, hardware, and gold anodized mounting brackets along with new end links (also urethane and gold anodized).
www.ebay.com
There are also stiffer bars if you want to go even further down the road race handling direction, 1-1/8" and 1-1/4" bars
There area couple used stock bars on Ebay right now for $75.....but by the time you buy new end link kits and mount pads the total cost will be close to just buying the whole new kit.