You have three options, two easy, one hard.

Easy #1: Sell your DX and buy an '86-87 Si. Drop in a fuel injected browntop ZC.

Easy #2: Harrass an importer into finding you a carburated browntop ZC. Drop that into your DX.

Hard #3: Convert your entire car to fuel injection using all the Si parts, including the gas tank, pump, and lines. Then drop in a fuel injected browntop ZC.