Cliff, you are right. NHRA outlawed them after '69. Still, one driver raced in two NHRA FC eliminator events. I'm talking about Marv Eldridge's ftrends topless Vette! He qualified for both Pomona (won by JJ-Clare Sanders) and Indy (won by M/T-Ongais). There is one other possibility and that would be the aforementioned '66 Chrisman Kendall GT-1 Comet. Jack's only opportunity would've been the '66 World Finals at Tulsa, the very first time NHRA offered a FC eliminator. But I don't have a report so I'm not sure if Jack competed (won by Schartman in yellow Steffey Comet).
The Secret Weapon raced at '67-'68 Pomona but that was prior to NHRA offering FC eliminator at the Winternationals. Years ago I asked John Jodauga why there was no FC eliminator during 1968 after NHRA offered them at Bristol and Indy in '67. He said the racer participation was so poor NHRA dropped them for '68. None of their first 3 offerings had full 16-car fields (including Tulsa '66). The '69 Winternationals was the first
full field. Still, NHRA offered no FC eliminator at the '69 World Finals.
Getting back to Gene Conway, he did win the '71 OCIR PDA event w/ a standard Vette FC! Gene was one of a handful of drag racers who changed their name for easier marketing. His real name was Gene Ciambella. I just learned from a draglist.com story that Gene got the name Conway during the time he raced the Destroyer Jeep. His inspiration? The actor Tim Conway who starred in "McHale's Navy!"