Make sure you change out the dual proportioning valve to one from that came from a civic with front and rear disk brakes. (otherwise, your car will have way too much braking in the rear; drum brakes require much more pressure than disk brakes for the same stopping power)

The brake pushrod has to be adjusted correctly (special honda tool to set the gap correctly). No gap and/or partly engaged master cylinder = super touch brakes. Not sure what too big a gap would do. Probably best to keep the current brake booster and master cylinder instead of swapping it for something more powerful.