while LT1s do tolerate a ton of timing advance, they're a 'fast burn' type head, but they dont run hot. same with a lot of aluminum heads, they want to be run cold with lots of timing. a modified LT1 usually seems to make peak power closer to 34-35 degrees of advance, and anything over that is usually just waste, but does depend a lot on what heads this guy is using.

LT1s are a very knock resistant engine, but that means they have a big grey area between peak power and knock. so lots of the 'add advance till it knocks then back it off' guys end up with those kind of numbers and totally botch the tune.

most engines, i've read, have a couple degrees between peak power and knock, the last LT1 i helped dyno tune had SEVEN DEGREES between peak power and knock (peak power on that one came on at 34 degrees total advance)