the Z1 engine will bolt to any 88-91 CRX/Civic transmission, but best to stay away from 88 transmissions due to clutch incompatibilty - the 89-91 CRX HF transmission has the best gearing for fuel economy - the Si transmission would not be a good choice due to its low gearing - the engine will not bolt directly into the 88-91 CRX/Civic chassis without first changing the driver's side mount that is bolted to the block - you need to swap the one from your old engine onto the Z1
in order to maintain the fuel economy of the Z1, you should convert the car to OBD1 so that you can use the P07 ECU from the VX - this would involve purchasing the OBD0 to OBD1 conversion harness and making the other changes required for the conversion - as stated above, if you have a CRX/Civic DX or Civic STD, you would need to do the DPFI to MPFI wiring changes to the engine harness