Dorian, I'm not familiar with the jet version but suspect that like it's big brother, you need to make sure the head is flat and in spec. Most have been planed to the point they are out of spec or too thin. If in spec and truly flat, make sure the bolt holes are clean and use new bolts with wider/heavier washers to spread the clamping force and add 10 pounds to the factory torque specs while using a known in spec torque wrench. Coat the head gasket with aluminum paint or head gasket copper gasket sealer that most auto parts stores sell.

I have aluminum heads on my Hudson's with good service using a lot of the great Advice already mentioned so i can only add use Grade 8 washers and recommend using KW Coppercoat Spray I feel is the best, then spray both sides a few times and hang the gasket until gets real 'Tacky' before installing and re torque aluminum head cold a couple of hot/cold cycles.

Aluminum heads require a special gasket - the one's normally used on cast iron heads, while they will work, can sieze up when used with an aluminum head due to the disimilar metals. I can't remember the difference but as I recall, hopefully correct, gaskets for aluminum heads have a copper insert around the bolt holes - somebody please correct me if I'm wrong.
What can happen - here's a story for you. A Chief Engineman I was stationed with while in the Coast Guard came back to the ship after a 2-week leave. While on leave he had helped a friend of his with a 1939 Lincoln do an engine overhaul. The engine had aluminum heads. They had been on for a number of years. The heads were locked to the block. Not even loosening the head bolts (or nuts, I've forgotten which) and running the engine worked. They ended up pretty much destroying the heads to get them off.

Hudsonly,
Alex B