I found the answer.. The answer is yes, and no.. There is no typical dimension, but they are all the same.. Enless they are different. The most common is 9 1/16"..
I spoke to Mike the owner of CWI today and he told me that from 1961-1987 the Salisbury IRS is essentially unchanged but minor changes in dimensions were typical from year to year and casting lot to casting lot.
The solution.. He would happily accept my return and make one to my specification, or.. I could as easily remove a small amount of material from the opposing ends of the tie bar and save myself the time and expense of shipping and waiting for a replacement..
I happily accepted the later as I had already done a fair amount of finish work (they were out of the polished bars when I ordered).. The result is I ended up machining .1875" +/- from the tie bar..
This is completely common and should have no structural impact on the assembly. Here is the finished product...
http://www.clubcobra.com/photopost/index.php?photo=2503
Regards,