Overdrive 833

The engine trans combo in my 74 challenger is not original. The trans came out of a mid to late 70's truck per the numbers on the side. Brewers told me that in order to get the shift pattern correct that the 1-2? shift plate would have to be turned upside down and the linkage would have to be extended. Does anyone have any information on this such as length of the extension that has to be done on the rod or pictures of it?