Throttle Cable

If I'm reading right, your problem is that the Jeg's bracket clamps on the plastic part of the cable instead of the metal sheath? I think I'd get rid of the Jeg's bracket. You can get a reproduction stock four barrel bracket for $33 that should work with stock or aftermarket intake. Also, they are easily modified to put the clamp where you need it.

MF224 - 1968-73 Mopar 340 Four-Barrel Throttle Cable Mounting Bracket

Also, AR Engineering has small block throttle brackets for extra tall intakes.

Throttle Bracket Kits | AR Engineering