Sadly, I highly suspect the MSD control unit.
If you turn the key to the ON position the dash lights should ALL come on-including the CHECK light. The CHECK light will go off after a few seconds. During this time you should hear a click and the fuel pump should also ru for 2 seconds and then stop. If this test fails-the MAIN relay may be to blame. We know you are getting power to the Starter relay and several other circuits.
The CRX does NOT use "fusible link" wires. Everything that I know of is either a fuse or circuit breaker. Having reversed polarity is definitely not good for any electronic device and it is possible that the ECU is fried-but not as likely. If that is the case, I have one available (PM6). I still think the culprit is the ignition box or if you retained it the Ignitor.