Might be a winter project and buy a Miata short shifter kit. I know some of the Miata guys rave about the short shifter and certain guys will even custom bend it for you.
Which guys? I recently posted a thread about my desire to reduce the length of my gear shifter on my 2016 Roadster as I find it sits too high and would benefit from being about an inch shorter, even though I understand this will make the throw a bit stiffer.
However, in doing so I will have to have the shaft re threaded.