Problams installing manual engine to auto box

Help, about to install an ex-manual engine to an auto, but having done some home reading the workshop manual. It tells me:

Drive plate - refit
1. Check that bolt holes in crankshaft are clean and dry.
2. Position spacer, less original shims to crankshaft.
3. Position a straight edge across spacer.
4. Measure and record distance between gearbox mating flange of drive plate housing and straight edge.
5. Repeat procedure on opposite side of spacer.
6. Add the 2 measurements obtained together and calculate the average.
7. Calculate the difference between the average figure obtained and 12.4 mm.
8. Select shims from the range available which equal the final figure obtained.
Now I haven't done this and when I reassembled the driveplate onto the engine I noticed the 2 shims are both about the same thickness, but other auto driveplates have different sizes. I doubt my local L/R spares shop has the range of shims! What is the consequence of not doing this?

what you need to do is make sure torque convertor is fitted correctly and measure the distance from fastening lug to bellhousing face with some form of straight edge across it both sides to get average distance on engine the rear most part of drive plate to rear engine face is measured both side to get averge ,say the distance of torque convertor is 30mm rear most face of drive plate should be 29 mm or a couple less .this is to ensure that torque convertor wheb gear box is fitted is not been pushed into auto box pump and there is free play between it and drive plate ,but not too much that torque convertor doesnt engage auto box pump