Aftermarket studs by any chance? My ARP ones need to be torqued to 85ft-lbs which is hard to do with the engine out of the car and you trying to hold it.
I don't think MLS gaskets are as easy to see "blown" as others. Since the engine is apart, I assume you plan to replace the headgasket anyway. Personally I'd just throw a new one on and see how it goes, and if you got a few bucks go ahead and get the head resurfaced.
I had an oil/coolant mixture going on, but it was due to tapping too far for the ls-vtec plug on the bottom of the head, making the wall between the oil/coolant passage a little too thin, and it not standing up to the pressure and cracking.
Either there's a crack in your engine, or the headgasket is blown... Headgasket is cheapest, so I'd start with that.