ok, i feel your frustration...but didn't say you were whining. that's why all of us are here, to reach clarity. no need to hold each other responsible because we're all in the same boat.
i agree completely: lack of standardization really gums up the works.
ok, i'm holding my dax throttle the same way...i see 2 philips screwheads (not nuts) the other half is threaded to accept them & has thru-holes, so a too-long screw wouldn't matter. the screws are long enuff to make a secure fit. you're saying the one you have has studs, then nuts? i see that'd be an unpleasant surprise. i bet he'd be interested in feedback about that detail. meantime, maybe make the best of the situation by removing the studs and using screws? if the holes aren't thru, you'll have to trim the screws to proper length.
back to the task...i'm still a bit lost about your ultimate goal. the throttle dax offers is intended to accept the fitting (see pic) and cable that comes with his kits. i think you're doing an apples & oranges thing, and frustrated that it's not working out?
innovation is what we live for here: you're looking to use your existing cable & curved fitting (not familiar to me, is it the grube combo throttle?) with the dax throttle, not made to be done, but if i had to, i would drill and tap the dax to accept the fitting i want to use. next problem would be, is the existing cable-end compatible with the slot on the dax inner parts?
are we getting anywhere now? let's see this through to solution...it's good for everyone.
edit: what i was trying to say and didn't do it very well was: don't blame dax, he offers a fine selection of "replacement" parts for his kits...blame the guy you bought your kit from for not offering compatible upgrades.