I think I'm keeping the alignment plate. You never know what you might need (or want) to do in the future. Same with the clutch alignment tool that I bought from RAM which is metal and seemed to be quite good.
The "A" length (back of transmission to center of U-joint) was 47 3/4". The paperwork said 44 7/8" c-c on the u-joints. Mine is the "Chevy" T56 Magnum, so if you have the Ford one, the bellhousing is shorter IIRC, and so is the input shaft on the transmission.