Hard to tell from your description but...
If there is no boss for the kickstarter on the right, lower, rear side of the crankcase, it should be a 1996 or 1997 motor.
If the oil screen plug is just a seven point, this means the bike did not have an oil cooler and thus is probably a 92, 93 or even a 94. But if the oil screen plug has a little knub conector ( this is for the oil temp sensor and rubber boot as MM998 pointed out), this means the engine is maybe a 94 and more likely a 95-97 motor.
The sound deadening gasket for the clutch cover appeared in around 96 or 97.
The only thing I would be concerned about is getting a 97 or 98 motor that came from a Monster, as those engines had smaller valves than the std 900 2V motor.
HTH