I have a floor shifter for my 1957 NAPCO with a 1st gear synchro Saginaw (7 bolt) 3 speed OD trans. Because the trans was a later model (1965) trans I ended up using bucket seats since I couldn't get the shifter forward enough. For what it's worth this in the info I got from Hurst, I just felt better about a Hurst rather than a cheaper conversion kit. I chose the first option, works well but did require some modifying:

From Hurst:
HUU-3667271 shifter and HUU-3670010 installation kit. It is listed for a Chevelle but it will work with your transmission and the stick has a big bend for seat clearance.

HUU-5010002 is your second option. It is the Indy SSA shifter for the 3 speed and has a slightly bent stick for the seat.