87 5.3 motor placement question?

[AllWaysThinking]

OK I made my own motor mount brackets to keep factory A/C and they moved to motor back 1 1/4". Then moved the slotted frame motor mounts all the way back that gave me 3/8" more from where my standard SBC was. I hooked up my Trans shell to made my trans mount and thought I would check my drive shaft length and I it came up 2" short!!!! I was running a 350 SBC and a 700R4 so how did I come up 2" short?? I thought from all the motor mount plates I saw it would move the motor back 1 3/4" I am only 1/8 short of that so how did I come up 2" short?? When got this truck nothing was right on the truck someone just throw crap together so I am not surprised that I am off. Do I need still need to move it back?? I put the fan on the motor and the fan shroud and the fan sat right where it should be. I am confused I will am some pic so maybe someone can help me out..