DOHC ZC into CRX SI is pretty simple - bolts right in using the Si transmission, axles, flywheel and clutch - you will need an upper radiator hose for 88-89 Integra - use the Si bottom radiator hose - vacuum line connections are the same as the Si - swap your Si engine harness on to the ZC and make the wiring changes at the distributor - see this on our website for wiring instructions:
http://www.zcspeed.com/SiZCwiring.pdf
i would strongly suggest you replace a few items before installing the engine, including the timing belt, water pump, front and rear crankshaft seals and oil pan gasket - these are realatively easy to change with the engine out of the car and a lot harder to do once you get it in and find you have an oil leak or leaking water pump - consider the timing belt a
must change - you might want to consider getting a new clutch assembly as it is also easy to change before you put it in - other things like valve cover gasket, spark plug wires, distributor cap and rotor can easily be changed once it is in the car