I read a few different ways of plugging the hole after the starter is removed none of which really appealed to me, they either cost too much or were not available. I set out to find my own solution, it had to be cheap easy to come by and easy to install. Here is what I came up with, hope this is useful to someone else.
I originally thought of just using a rubber stopper. But, I was worried about it falling out. Then I realised I could use a freeze plug, but I couldn't find any in stock that were 30mm and again I just thought they cost too much. I went to the hardware store and found a 1" copper cap for plumbing, was just over 30mm. So I bought it for $2.50.
Took it home and cut it down.
I used a piece of paper to gauge the thickness and cut the cap to match.
Massaged in place with a hammer and socket, the socket needs to be a little smaller than the copper. I also coated the copper with some grey RTV before installation.
I think it looks pretty sweet, I'm not using the stock cover or the chrome cover that was on top of the starter. Making my own out of a piece of sheet metal.
Thanks for looking!