Be aware that hanging pedals need a lot of support, particularly for brake operation. The firewall alone is not strong enough to withstand a hard push during an energetic (panic!) stop. On the round track cars, we usually scavenged a complete clutch and brake pedal and pivot assembly from a 1970's or later pickup truck, and built a well-braced structure to mount it between the dash and the firewall. Clutch linkage can turn into quite an exercise in geometry unless you can go with a hydraulic release system and add a single-reservoir master cylinder for the clutch. One system I used a lot on the dirt track cars was the master and slave cylinder setup for a mid-1960's Dodge pickup. Those parts are still available from some of the online parts vendors. Try a 1965 Dodge D-100 clutch master and slave cylinder as a reference.
Jerry
