Are you looking for an Open pour or injection?
I make some big baits, but I think a body that big will give you fits with denting in an injection mold
You may be better off to make yourself a Plaster Open pour mold
These are only 8 1/4" with a 1" dia. body Injected... They give me fits with denting
Here's some 12" baits that are Open pour
I know they kinda stink but these were the 1st molds I carved