You do not need to purchase from the vendor I provide links for but here are the parts:
Lower
This comes with two gaskets but they are handy to have around:
Upper
I would suggest that you do [not] use the cork or rubber end pieces of the lower intake gasket. Eliminate those and use a bead of your favorite black RTV. I prefer this:
www.permatex.com
With aluminum heads, there is always a small gap between the engine deck surface and the bottom of the heads. It is just outboard, on each side, of where the cork gaskets [would] go if you used them. You [must] ensure you visually ID this gap and fill it with RTV when you run the bead along the front and back. [This] is likely where your current leak is.