The throttle cables would/could be universal. The controls are mfg specific. Someone like Teleflex may make a multi-mfg type of control, but I doubt it. I'm no expert, but the electronic hook ups are probably the issue.
Im pretty sure they are brand specific. So if you get a merc 9.9 and move to a 40 merc it should be fine unless there are things on the new motor that isnt on the old one. Such as the way the choke works or power trim.