I have a 1965 barracuda it had a transmission with 2 cables and a floor shifter . I changed the transmission to a newer one , what can i do ?

'66 and up consoles don't fit between '65 and earlier seats, that's why the factory narrowed the seats in '66.
OP, use the search feature, there's lots of threads on here about adapting aftermatket shifters into the '65 console, especially the Hurst Pro-Matic which looks basically stock.
Here's some to get you going:
64 65 Dart shifter console. What shifter?
904 in 1965 Barracuda