There are a lot of "classic keyboards" samples available, but you would need a sampler to use them.

It's interesting that you would want to sound like that. The organ players of the period mostly thought the sounds made by the portable organs (Vox, Farfisa) were annoyingly cheezy. They settled for them because a real organ was expensive as hell and took four guys and a truck to get them anywhere. Some bands did it anyway.

The best rock keyboard player is Garth Hudson (The Band). This has been verified by God and is not debatable.