A good mechanic can do the HG swap with cometics for around $1600. Supply other gaskets and save $150-200. This would be a speed shop that also has the ability to machine the heads flat. You will need to so this. I'd use cometics for the peace of mind. They seal a whole lot better.

 

I would do both sides!
Felpro all the way. Cometic is $$$ and not needed in a vehicle such as this. No name brand gaskets are generally inferior.

You can get away without machining the heads if you haven't overheated, but it's a good idea to have them done if you have. Whole idea behind machining them is to remove the warp from excessive heat.

 

I had that happen with a 4 cylinder car. Quite a bit cheaper to fix but still expensive.

 

Do both sides absolutely. I can not agree with the felpros. I've replaced HGs on these trucks and both the Mopar and felpros leaked. The cometics do not. They have a different design around the water jacket ports where the other gaskets are missing the top sealing layer of gasket material. Don't go cheap and waste your time. This is my warning. Also that's not correct about the heads. Aluminum heads on an iron block will warp over time from heat cycling, and sometimes aren't straight from the factory. At the very least have them checked. If it were me I'd also have them dye checked for cracks just to be certain.

 

I use Fel-pro gaskets myself and I always use Permatex Copper spray on both sides. It fills is any imperfections in the heads and block. Just used that set-up on my latest project when putting Trickflow aluminum heads on the Mustang and it worked just fine. The copper spray makes a big difference. Been using it for over 20yrs and have never had a failure yet.
Proper torque sequence is a must as well.

 

Yes, the copper spray can make up for it, but if it were me I would just spend the bit extra for the good stuff. FWIW the mopar gaskets with the copper spray did not seal though..