I'm from Dallas and have never heard of either of those cats...my pops did work with and for everybody back in the day (Gene Snow, Raymond Beadle, etc.). Calvert was a name, Buddy and David without question, Jimmy Allard, Charlie at the Farm Shop, Dennis Wells...none of those guys were LC2 builders though. I mentioned my guys because of first hand knowledge with turbo Buick stuff...Trevor and I both taught competition machining and built Buick engines here in Houston for LC and Kurtz (and all the stuff for me and my shop)...not to mention Trevor having his own T for a good while that he and Watt put together on that end of the world.
As far as warranties that someone asked about...don't know the policies of those shops. I can tell you that "real" race stuff doesn't carry a warranty typically...but street car stuff will within reason. As competitive as the LS market is now, shops like Mast and LME are offering warranties on their engine assemblies...but as with anything like that, there are qualifiers to keep that warranty valid. Turbo takes a shit and trashes the bearings...sorry, that one is on you.
I'll do it for you if you want to make a trip to Houston....up to you.