ooo boy..
you got some fun nightmarish work ahead of you...
1st off)
Since you bought an OBD1 DOHC ZC engine aka 3g-ZC, yer gonna have to do a few changes to it so it will be compatible with your EF.
2nd)
you're gonna have to convert your DX to Multi-point Fuel Injection (MPFi), just like the Si model has....have fun doing this !
Motor mounts:
reuse ALL of the engine mounts from your DX motor on the 3g-ZC.
Transmission, Clutch, Shift linkage, & Axles:
You won't be able to use the 3g-ZC tranny because of its Hydro type configuration. So, you're gonna have to reuse your lamer DX tranny on it, along with your complete DX clutch components (flywheel, pressure plate, disc, throw-out bearing etc), axles, and shift linkage. It will ALL bolt up to the ZC engine.
*catches breath*
Once you've converted your car to MPFi....
ECU:
You can use any 88-91 Si ecu (PM6) in stock form to power the engine, or if you want to have it reprogrmmed to PM7 ecu specs you can do that too, but it has to be a 90-91 PM6 ecu. 88-91 PM6 ecu's are non-programmeable. If you come to this point & would like your PM6 chipped to PM7 spec hit me up =)
(PM7 is the JDM ecu for JDM 89-91 civic/crx's equipped with a 2g-ZC DOHC engine)
Wiring & Distributor (dizzy):
As mentioned before, you need to convert your car to MPFi spec in order to make your car's wiring compatible with the ZC engine. One option now, is to choose whether you want to stay OBD-0 or go OBD-1. If you decide to go OBD1, you still need to convert over to MPFi....there's no escaping this!!!! But if you do go OBD1, you'll save a lotta hassle off your back trying finding OBD-0 parts that you need in making the 3g-ZC compatible to your DX. There's a hanful of perks going OBD1 (better ecu programming & electronics mainly).
Since you have a 3g-ZC, you can't quite use the dizzy off it because of the OBD/OBD1 differences. You'll need to find an 88-89 integra distributor if you want everythign to be clean & compatible, otherwise you need to find a 88-91 Si dizzzy and modify it to work on the ZC engine -- this can get a little complicated though...so I suggest you try & find a 88-89 integra dizzy.
Did you get a P29 ecu or any ec for that matter with your ZC engine at all?
...this all, is a loose ballpark of things you'll need to do in order to get this ZC engine to work in your car. If I were you, I'd try and return it and get an (89-91) 2g-ZC engine+trans, which is way more compatible with your DX. but the MPFi conversion still needs to be done!!!! haha...