Basically, 2002 - 2004 243 LS6 heads, in usable condition along with a usable (the less miles the better, obviously) LS6 camshaft. I'm not sure, I need to do more research, but I THINK the 01 - 02 LS1's got the LS6 oil pump but I have to double check that.
I'd prefer to buy locally so I can inspect the parts themselves unless you know that the person who's selling the parts is reputible and won't mind a return on the parts if they don't pass mine and my machine shop guy's inspection.
There's a corvette forum on LS1Tech but I rarely, if ever, see the 243 heads up for sale.