Take a read of David's Cal 11 article, where he looks at whether this period Heuer designs could be from Heuer themselves or their then owner, Lemania:

http://www.calibre11.com/heuer-lemania-part-two/

We know that Lemania were offering the cases to other manufacturers for some of the watches. I see no reason that this isn't a genuine Bucherer (just as they are genuine Bucherer Monacos as well as Bucherer Monacos with a sudden Heuer facelift!) and worth buying if the price is right.