I installed mine with the Garlocks, because that is what came with the 'kit' I purchased (I use the term kit very loosely). The plus to them is they were a good template if you want to port the LIM. On the downside, they probably should have RTV added to the inside edges and they stick out all over the place on the outside. The outer edge doesn't match the intercooler at all. I would use the GM gaskets if doing it again.
Don't worry about water wetter or stuff like that yet. Match sure you route the hoses so the won't get rubbed open by the belts. I thought I had it right, but three weeks later lost all the coolant when the belt rubbed the hose. Concentrate on getting all the air out. I used clear hose and a T from a radiator flush kit. Add about another foot of hose on the T and use that to add coolant. It will act as a bubble trap, coolant reservior and leave some air in it so the coolent can expand when hot. Otherwise it will leak out somewhere else.