It would be helpful if you could state your purpose including your film application's exposure time, spectral characteristics, illuminate levels etc.
Even without this information I would suggest following approach KISS: keep it simple.
The most accurate and reliable mechanisms can be very simple: ½ to 1/100th of a second use guillotine drop shutters. Gravity is quite constant in one location. For 5 seconds and greater use synchronous motors in timers i.e enlarger timers. They can be very repeatable. Accuracy is not as important as repeatibility if you are only using one time duration.
It seems to me that a common electronic flash is far too variable. EG&Gs are good but they are specifically designed for the purpose. Typical flash units are designed to perform to very different criteria.
Your Ilford light source has its own problems.
A simple solution assuming you are using materials that do not have RLF in the 5 second range: use a low wattage light bulb controlled by a electro-mechanical timer that is repeatable in the 5 second range. Many enlarging timers can satisfy this need. Put the lamp in a housing like a safelight. Add neutral "filter material" if the light is too bright. Bond paper provides about a stop of density per sheet or increase the distance (start at 10x the diagonal of your exposure plane) between the light and film.
To check out the performance expose ten pieces of film and process them identically. Processing at the same time would be best.
see my website: www.makingKodakFilm.com