Hey Matey,
Good buy.
However, I wouldnt go by saying that " 3" is certaintly too small". Jewies are oppurtunitistic feeders and IMO will hit any good plastic that is in front of them - as long as they are hungry.
I have caught some cracker jewies on 3" Shrimp and 3" Minnows - one of my biggest jewies went 16kg cleaned and was on a 3" minnow up at Roseville.
However, in saying this, I have had more success with 5" plastics and BIG shads.
I rekon, that its fishing and there are no rules. Whilst some plastics may outfish others for species, there is no rule saying that one species wont eat a different type of plastic.
Good luck and look forward to the report of that big jewie!!