Doug,
I'll have to inquire about source of plans. But as I recall, the basic SP plan is in the collection of the California State RR Museum. Our construction crew also measured, etc. the table at Laws.
The Laws table is said to be the only such table on the SP to have a outter support rail in the pit. This probably was added to help it handle heavier engines on and off the table and not quite in balance. The turntable at Nevada State RR Museum also has the outer rail.
At the time we had our castings made from the NSRM paterns there were three outher sets cast up. One was used for the turntable at Folson, California which was completed last year. The other two went to (I believe) El Dorado County Historical Society; I'm not sure of the status of that project.
Brian