Er, well, just like the standard .020.. I know it's not gonna make a huge difference in performance but I'm going to be using a used core block so I know it's gonna need work anyways, might as well get totally fresh walls right..? And I suppose I should come clean on this, I don't really know jack about rebuilds
(I have been doing my homework though) so if you guys can point me in the right direction as far as what needs to be done with a rebuild aside from the assembly I'd really appreciate it! I mean, I've found enough write-ups on the actual assembly/disassembly/measuring all that good stuff, but everything just says "after the machine shop" not really what the machine shop actually did.. 
Sorry if it's a redundant question lol