Some of the sales on BaT are mindboggling (ref the recent car that sold for $108k!),and the comment sections are a great mix of auction participants (and non-participants) that either blow smoke up the vehicle's backside unnecessarily ("this is the best I've ever seen, surely goes for >100k??"), or get incredibly hung up on what are seemingly less-important details.
Having said that, is there not a fairly simple test here - if you were presented with two cars at the same cost, identical in every single way, mechanically and aesthetically, and with respect to originality and performance. One has a replacement engine, one has a numbers-matching original engine. Which would you choose?
If the answer is the one with the original engine (as it would be for me), does that not mean it is more desireable to the buyer, and should command some premium, however small?
Having said that, I do agree that there are more important factors at play when choosing the right car.