"using wedge-shaped combustion chambers": the author never saw one, or even read anything on the subject. The chamber is many things, but a wedge isn't one of them. If he mistakes "squish" (which it has) for wedge he should expand his employment opportunities.
WRT SU jetting: yes, in most model H the idle mix is controlled by main jet height, but the remaining range of engine speed, load and vacuum mixture is determined by needle profile, and there are several hundred needles. If you don't have the correct one, or your engine has significant mods, the car maker frequently published alternative needle reccos for rich, lean, high altitude, race etc. Otherwise you do R&D...
WRT dual valve springs - there is a specific part number in Group .303 for "1953-55 Corvette 6 cyl.", but I have no other information.
