240zboy

I am in need of a 7 tooth drive gear for a wc t-5 but they seem to be impossible to find. So I was wondering if there is an alternative way to have my mechanical speedometer work? Its a smallblock swapped 240z but running a chevy speedo cable adapter.
I am scared the only way to get it to work without getting the right drive gear is to put in a gps speedometer which will cost around 300 dollars and require my dash to come off.