You want a D-series clutch and flywheel. Save yourself some headaches and get the same year clutch and flywheel as your transmission is. For '88s, the input shaft has 21 splines, and the clutch disk and flywheel friction surface are 190mm; for '89, it's a 20-spline shaft, 200mm disk;; for '90 and '91, 20-spline shaft, 212mm disk.
If you've got an '89-'91 transmission, you can use any of the '89-'91 clutch and flywheel sets - just make sure the clutch and flywheel are the same year!
I believe Honda finally stuck with that 212mm size for the later-model D-series as well, but the '88 and '89 sizes screw some people up when they assume that all D-series transmissions are the same.