Sure brings back good memories I had a 68 coupe with a 427 "Tunnel Port" That I raced in Super stock @ Oswego, Il and US30 Dragstrip(In.) in midwest in 70 &71 Best time was 10:85 135mph. I had a Art Carr clutch C6 trans setup with5:14 rear gears went thru traps @ 7200RPM
I have been collecting parts to do a remake just about have everything except going with differnt trans now and the Tunnel Port is 494 cu in. probaly a year away because finishing a couple other projects first. I like the fastback better than coupe but coupe was all I could find and afford back then. Good Luck with your project.
George