Scoobyturbobug

my ecu has buggered up it fails to start from cold i put a spare ecu ive had lying around the garage on and the car starts fine now, the ecu is off a legacy turbo though will this cause any problems to my engine its a 94 uk spec impreza? if it will what ecu would best suit it? i would do a search but it dont work so any andice would be greatly appreciated as it needs fixing fast.
Thanks