Jeremy:
Good luck with finding a direct replacement,based on my search I suspect
possibly discontinued??
You may need to do some backyard engineering, before I repowered and replaced the original Mercruiser brackets on my transmissions for the shifter cable attachment I had to use a piece of stainless steel angle as the shift cable's holder along with some Teleflex cable fittings.
In the below photo you'l see the stainless steel bracket I 'engineered':
And in the below photo you'll see the Mercruiser bracket of mine whose cable attachment stud had corroded beyond 'service':
Either which way a bit of lateral thinking and you'll be able to effect a repair/solution.
The bracket does not have to bear a major load as such,in fact if you wrapped the existing shifter cable on to your broken bracket with some stainless steel wire [heavy leader wire would do] it would likely last a long time,the plastic cable ties will eventually give way!
Else a local machine shop could fabricate a bracket for you.
By the way Tranmission Marine in Fort Lauderdale are a good source for all things Borg Warner/Velvet Drive transmission wise
www.marinegears.com