There is no other gasket that goes around the bolt holes. The one gasket is all that is needed for these engines. I would wager that your dead sticks are being caused by gaskets in the head of the engine. As others said above, it is common to have head bolts loosen a bit as an engine breaks in so you need to check them occasionally and tighten them as needed. An engine such as an OS really isn't fully broken in until it's had quite a few tanks of fuel ran through it (15-25 is a good estimate) so you need to keep checking the engine as it continues to break in.
Do as was instructed above when you reassemble the engine, use a cross pattern on the head bolts as you tighten them back down and make sure they are all evenly tightened down. Then restart your engine and check for your fuel leaks again.