As I mentioned B4 there should be a rubber block for the clutch pedal to rest against,
AS your car w3as converted, you may not have it. see it here as "clutch"
I'm not 100% on your BBC but My SBC the clutch return spring goes to the subframe, mine has an extension link. ,. there are a couple holes made into the frame for this. Its the straightest path, unless headers are in the way.
Note: the clutches were known to stay disengaged, on the floor when shifting hard and fast. Old school racers used to tie or strap thier left foot to the pedal to ensure it would engage when they lifted their foot.
67 68 69 Camaro & Firebird Clutch & Brake Pedal Bumper: Camaro clutch pedal stop rubber bumper. This bumper is installed on the pedal housing
This is a Camaro site - - but has really good "catalog" pictures and list 'Factory part numbers' ;
good for making sure you get the correct parts (really good parts descriptions) .
Plus, I have bought parts from them = good service = and, I have "returned parts - with good results" .
and, Thank you for posting up your Part Numbers , could very well help someone down th' road . . . .
plus all your install pictures .
On my "return spring" - - - mine is attached to my sub-frame "hole" , under or near my motor mount , (a six cyl car) , hole may be there .
using the ' long rod and flat link ' . . . My inside clutch pedal DID - NOT have any spring .
I do have the rubber stopper, and the because of headers I can't attach to the exhaust manifold with the extension bracket and spring, and the SBC variant with rod and spring won't work either.
I have been playing with the stainless steel band clamps on the header tube in the front of the clutch fork. I should get it to work, tried shortening the spring, to get some pre tension, as the new mounting location is closer to the clutch fork, so I am not getting enough force to really pull the fork + linkage to pull it all the way back to the rubber stopper, if that makes sense. I really need a spring with same travel, but higher force. It is just a matter of trial and error.
All welded in, and I also patched up some random holes in the floor from probably previous attempts to bolt in bucket seats. Ugh patching up holes is something I need to practice more, so tedious with old sheetmetal.