Although I do not have an immediate solution to your problem, it was refreshing to know that there is another person who is longing to play Omni-Play Basketball. I had an Amiga computer several years ago and I played it all the time. It became a personal favorite. However, over time my computer began to increasingly break down, and than pump money into a fading system, I decided to sell it and all my software.
The memory of the game did not fade though. Once I bought my Dell computer I downloaded an Amiga emulator and several games, including Omni-Play Basketball. I was so excited when the game ran and seemed to be 100% operational. However, to my dismay I discovered a small but crucial bug in the program... during a timeout (when you make substitutions, pick strategies, etc.) the screen would not scroll up, so that it was impossible to see what you were doing.
The rest of the game though... the sounds, graphics and animation and EXACTLY the same as I remember. The game-play itself is fine.
I don't know how badly you want to play this game... if you just want to relive the memory or if you want to start a quest for the championship trophy. To me, this is the ultimate tease, being so close to playing one of my all-time favorite games, but not close enough to have total control. I'm seeking a fully functional game. I know you played the Commodore version, but maybe this would cover your needs?
I have also seen Commodore versions available for download as well. I haven't tried these yet, but if I can't find a good working copy I may explore this option.
There are several sites where you can download the emulator and the game. WinUAE is the name of the emulator I use, it has an excellent readme file to get you started.
If you have any luck with an emulator version, or if you know of any place where you can purchase a PC version (did they even make a PC version?), please let me know by posting another message. If I find out anything more I'll do the same.