That is a nice offer Rick.
The actual test we looked at was run Swindon to Reading West to Westbury. All of which is on Paddington to Penzance route but unfortunately the gradients on that section do not match real world closely enough to try to replicate the tests on that section of route. Certainly it would be interesting to see the results with 71000 which has been the subject of much fiddling for the past month.
However before we say yes, I think we had better see if there are any other tests we want to replicate there. It might not be worth the effort if we are only going to use it to test one locomotive. Having said that however, there are plenty of published logs of GWR locomotives running between Swindon and Paddington so it might be useful if we want to do performance tests on a GWR loco.
Wait and see what the other members of this discussion have to say, not least our CME steamer1960.
The only snag is that we would probably also want Kings Cross - Peterborough to do road tests for LNER locos! (Mid East UK does not have gradients out of London.)
There are however plausible routes for some LMS and some SR road tests.