Use the Felpro print O seal gaskets (blue with the waxy looking coating) with a thin film of RTV on both sides around all the coolant ports.
RTV or Right Stuff the corners and both ends instead of the cork, and also use sealer on the intake bolt threads.
Most feel that sealing the threads is good enough, but I like to use sealer between the bolt shaft and heads as well, as it keeps oil from weeping between the gaskets and intake allowing oil to come up around the bolts even though the threads are sealed.
It also helps to set the intake on dry first, and find out what the front and rear gap is going to be so you don't undershoot the height of the sealant and have a leak.
Also note that left front corner (passenger side) of the intake where it mates with the China wall, as they come together a little strangely in that corner.
I try to do the sealer and get the intake on as quickly as possible after the China wall beads so the sealer actually sticks to the intake when it sets down.
The chances of it leaking is much higher if you let the sealer skin over before the intake goes on.
I have only done about 50 of them, so take my opinion with a grain of salt.:D
Also my opinion is to practice porting on something that doesn't have to be used as dukeboy mentioned.
It's just WAY too easy to trash a head when beginning.
BTW, I only EVER use red RTV on thermostat housings with no gasket and never have leaks there either.
Put it together with the sealer wet, and wipe off any that seeps out the edges, and it should be ready to go as soon as it's assembled and filled.
Also, on the thermostat, do yourself a favor while it's out and drill a 1/8 hole in the plate of the stat and you will never have air bubbles in the engine when refilling with coolant.
The hole lets the air circulate out before the engine ever warms up, removing the possible burping out of the coolant before the stat opens.
Here's an example when done and running.
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