Welcome to the forum.
On the surface they would seem to be a straight swap with the ECU as well....don't think the ute factor really matters as long as both were autos first. Try ringing some Brisbane wreckers who specialise in Commodore and tell them you were thinking of upgrading your 98 ute to a later engine - they should be able to give you the proper answer. Toowoomba wreckers such as City Auto Wreckers may also go (can recommend them). Access to a hoist and plenty of tools etc will be needed!.
Good Luck.
"If anyone disagrees with anything I say, I am quite prepared not only to retract it, but also to deny under oath that I ever said it." --T. Lehrer
"The secret of success is sincerity. Once you can fake that you've got it made." -- Jean Giraudoux