If nothing else, a local machinist/engineer should be able to help you out with fabricating a safe replacement.
I agree that it's probably less expensive to replace, but I don't know how easy these are to find or how dedicated to the car OP is; so figured I would provide a last-ditch alternative "if nothing else".I think the OP is missing the tow arms, as per her above post. I believe she would just like to buy replacement arms if she knew the brand of base plate. That option could be more expensive then just buying a new complete kit.
I don't know if it would be cost effective for a machinist to just fabricate the tow arms. That is if a machinist is known to the o p and is will to take on outside work. I had a piece of Steel that I needed cut to specific size couldn't find a local machinist to do it and this is in Las Vegas.
IT may be more cost-effective for the OP to buy a whole new tow setup. Which would include a new base plate correct?