B-square makes a version of a mount. I don't own nor ever have owned a cetme fal or hk91. None of them lend themselves well as all are cold war era guns and weren't meant to ever have optics.
From quick pokes on google I wasn't seeing any "must get this mount it works great" type stuff.
Someone that has some experience with em may pop up later this evening.
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...
"I crapped my pants to avoid the draft!!" -Ted Nugent