all of the 88-02 D-series SOHC 1.6L engine blocks and heads are interchangeable, just like the B-series DOHC engine parts. If you want more power out of a DX, honestly your best bet is going to be just putting in a complete D16Z6 or D16Y8. The DX blocks have a shorter piston stroke, so whether or not you put on a VTEC head, you won't have the power of a stock Z6 or Y8 engine.

If you want to stick with a SOHC engine, a good engine combo to go with to get more power than a stock SOHC VTEC engine, is to combine a D16A6 block (88-91 CRX Si) with a SOHC VTEC head. The A6 block uses slightly domed pistons (sohc vtec engine has dished pistons), so you get higher compression than a stock SOHC VTEC. And if your civic DX is 92 or newer, a SOHC VTEC ECU will plug right into the existing harness. You'll probably need to wire in two more injector wires, though. If your civic is 88-91, Zdyne makes an ECU conversion so that you can install the VTEC head, and it will run with all the factory safeties and fuel curves and such.