They might have made hei that wasn't on the cap, but not in 85. An 85 should be and in cap coil, unless its aftermarket, mine is on my 85. MSD makes a cap that is set up for external coil for hei. I wouldn't get an in cap coil. The internals (coil) are more expensive. Just get an MSD cap, coil, rotor, and coil wire. It'll boost your performance, and its not that expensive. The MSD cap & rotor is around $25, coil 32, and wire should be pretty cheap. I'm assuming that you have one of the canister style coils.
My Chevy isn't broken, its just out of gas.