71 Ford 300cid straight six dies like it loses spark for a moment? Why is this happening?

It starts OK and runs well. I've had the carb rebuild, total tune-up. Timing is
good and have also replaced the coil. Only thing I notice is while using the
timing light, was when the motor would cut out and start acting up the timing
light would light up. Hence my reason for thinking I'm losing the spark
somehow. The problem is intermittent but very frequent.