4 speed tunnel position question

we are just about ready to install the 4 speed tunnel in the Dart Sport. I need to know where exactly this thing goes. We will not have the engine and tranny back in the car till sometime in April and would like to get the tunnel welded in before we take it to the paint shop next month. What is the procedure here from transforming from the automatic to the 4 speed. I don't know exactly how far back from the firewall to align the hole in the tunnel for the 4 speed to fit. I know once it is fitted, we need to cut the floor out underneath the tunnel, weld it in and seam seal it but where does it position exactly to make sure shifter will come up in place. Told you guys I will need help with this. LOL Pics and dimensions and links and if someone wants to come and do it for me, that's ok too. Thanks,Bill