Adjusting 250 four stroke throttles

My brother has a 29ft.Century with a pair of 2005 250's. When running in the 4,000-5,000rpm range the lert throttle is about one inch ahead of the right throttle, which makes the "sync" a little difficult with one hand. How/where are the adjustments to correct this? Also, can the 2005 engines be retrofitted to the more modern system where the computer does the syncing?
Thanks so much

[boats.net]

If it's a mechanical control model then check the throttle cable adjustments at engines, adjust cable ends so both motors are same.