A500/A518 to Gen-III

How is the kick down being addressed?

Are you planning DBW or DBC?

If you are doing DBW just use your throttle cable hooked up to normal linkage that is not hooked to carb.

I thought I saw someone just drill a hole in a DBW pedal and run a cable thru it.

There are solutions out there to make whatever you are doing easy. Thankfully lots of dudes have done the swap.