The Monster 1000, 1000SS, Multistrada 1000, Sport Classic 1000 etc all use the later 2 plug ECU, but are all Duel Spark motors.
It could however be possible to use the wiring loom and ECU but just use single plug coils instead.
But, you'd need to get the immobiliser in the new ECU disabled to let you run the older clocks, as the 1000CC bikes need the combination of ECU and matched clocks to run the immobiliser.
Nasher.