for an easy swap, you basicly have 4 choices for the 1g CRX:
1. JDM Browntop ZC - 135hp
2. EDM D18A8 - 120hp
3. USDM D16A1 Blacktop - 118hp (88-89 teg)
4. USDM D16A1 Browntop - 113hp (86-87 teg)
The JDM and EDM motors are a little tough to get...they run about $600
The USDM Blacktop motor requires some wiring changes'..VSS, ect
The USDM Browntop is the easiest to swap in and you can pickup a motor and tranny from a junkyard for $300 all day.
Also, if you do swap a 1g teg motor in, you'll need the tranny (the CRX/Civic tranny don't bolt up to the EW/1g CRX motors), ECU, axles, and HUBS. The integra axles don't fit in the CRX spindles...the plus side is you get bigger brakes.
redpepperracing.com will be your friend if you pursue any of this.