i have done a lot of research regarding this swap, i have a question regarding the transmission and torque converter

I am swapping my seized engine on my 2005 Ford E250 4.6L V8 with a 2006 ford e250 5.4L engine - my question is that the 5.4 uses the 6 bolt torque converter and i have the 4 bolt torque converter. This transmission man who owns a tranny shop told me just swap the 6 bolt flex plate from the 5.4 with a 4 bolt flex plate for my size tranny from another 5.4 engine. I am wondering if anyone has done this before and have you had any problems with the tranny? Will there be any problems with the torque converter that i am using from the 4.6 with the 5.4? Also heres a stupid question but i thought it may work... the wiring of the 5.4 looks identical with the 4.6. Can i just use the wiring harness from the 4.6 to run the 5.4 or if i use the 5.4 wiring will there be any troubles? My tranny on my e250 is a 4R70W and the 5.4 had the 4R100.

I also know for a fact that in 2003 Ford was using the 4R70W tranny for the 5.4L V8 in 99% of their vans/suvs/pickups

Please help.

 

Your best bet regarding compatible wiring harnesses would be looking over the respective EVTM's of the affected years. Pin out circuit locations are often times changed between model years and even engines. Even though the connectors will physically mate up whether one year's circuits may be wired differently.