Sorry about the delay getting back to the thread, just got in from night shift. http://www.ebay.com.au/itm/262823813516
The last one of these I saw sold on US eBay for around US$875 the one before (same seller) went for $600 or so.
I doubt the liner could be removed as it is part of the head gasket sealing surface and the big deal with these was the casting was done around that liner for heat transfer.
The auction will end while I am asleep so will take a look this afternoon.
This one is already +0.050" apparently so going to +0.060" may or not be possible or wise.
+0.040" does seem like a sensible limit.
Would be a nice but very expensive addition to the 1957 TR6.