thanks. that sounds good. i don't have a caliper at home for measuring but according to the highly accurate tape measure (lol) i have similar measurement. i *may* have found a solution to my rotor issue. i was scrounging around in my garage and noticed that samurai rotors have slightly different sized (width) contact tips depending on the brand. i was able to match up a rotor contact tip from a honda 1.5 carbed engine (same length tip as the rotor from the 83 prelude i got the cap from) to fit an old samurai rotor button. this *should* get me to where i need to be.
lets see the mess of parts i am using for the ignition on my carbed swift gti engine: 91 swift sohc vac advanced distributor (was really hard to find), 83 honda prelude disty cap from a hitachi non-tec car, plastic 87 samurai rotor button (appears as if the borg warner has the correct width contact), 86 honda civic 1.5 carb fed emmisions rotor contact tip (unknown rotor brand at the moment).