Hi not run one in a mk1 , but pectel t2 is a good upgrade , fully mappable and has a few features but not overly complexed like the more expensive ecus. Does a good job. Ian used t2 on all his engines that ran big power for reliability and he used Ahmed and Harvey to do the mapping and dyno so you couldn't get any better. I built most of ian pectel t2 looms for many different cars including mk1 focus and I still run t2 on my engine and most probably will carry on as it's a cheap Motorsport proven Ecu.
Let us know if you need a loom lol

Cheers paul