This is a update on the Pulse Width Monitor that Steve Ravet posted several years ago. This one uses a built in module to measure the on and off times of pulses on pin-13 (RC2). There are no interupts to handle, it just counts clock pulses on a logic one or zero on pin 13. In this case the 4 mhz is 1 mhz internally (instruction cycles). The display is a 2 line x 40 character Hatachi 44780 type that is widely available, a smaller display can be used, a 2x 20 display would work as well.
I've tested this on my LT1 and it seems to work well see attached jpeg, with the monitor in action.