There are couple of options for the throttle pedal. The Hawk can use either a mini pedal and cable or as I have Gerry supplies an original throttle pedal. This fits through the roof of the footwell and has a cast housing sitting in the engine bay to which you connect the linkage to the engine.
It is a bit hit or miss getting the location right. I messed up initially and made the hole in the wrong place! I should have taken more notice of the blog of Jon Tower who states it should be about an inch from the end of the footwell. Still I got it right in the end and not too much damage done! I added a aluminium plate to cover the excess hole, you can just see it here.
Throttle pedal in location
Throttle linkage
Hawk 289 FIA AC Cobra Replica - St Piran 
You see the little hole in the pedal arm, just before it goes through the roof of the foot box? I’ve got the same pedal and am about to fit it – do you know what that is for? I think it is for a return spring, but none was supplied. Presumably a return spring there would be extra safety if the return spring on the carb ever breaks – it might stop the thing going permanently full-throttle. What do you reckon?
Yes it is for a spring return. They are often not fitted depending on the carb arrangement. I have one to fit just not gotten around to it yet!