Need tips on starting old engines that sat for 6 years

[akintosyali]

Purchased a 1965 H41 DC. Got 2 Chrysler 426 gas engines. The boat has been sitting for the last 6 years. I am working on bringing the boat back to life.

Got new batteries, Changed the spark plugs and wires. Changed the oil,
(Working on having the old fuel sucked out and replaced) this week. Engine does turn with a wrench...

Before I push the start buttons, I wanted to get some tips from anyone who has been in my spot. Any suggestions? warnings?
Thanks,
Akin

[Genesis]

Pull the plugs, put about a teaspoon of oil in each cylinder.

Roll over the engines by hand, ignition off, using a wrench on the crankshaft pulley with the plugs OUT to distribute the oil. Make sure the engine rolls over easily and nothing "hits" (no valves stuck, etc)

Get a little pony tank (e.g. one of the 2 gallon plastic Tempos) and a piece of fuel line appropriate to connect it to your system. Go get a couple of cans of SeaFoam at NAPA. Put a bottle of SeaFoam in 1 gallon of clean, new gasoline. Change all fuel filters.

Hook up the pony tank to your system.

Start up on that mixture. It will smoke like a banshee; the SeaFoam cleans out the entire engine and fuel system, including accumulated carbon. Run about 1/3rd of the mixture through at the dock at idle, then shut down. Wait 20 minutes for the mixture to soak in. Start up, run at fast idle for the second third, shut down and wait again.

Repeat again with the last part of the tank.

With the old fuel gone and clean fuel in the tank, that should pretty much do it.

The SeaFoam treatment is something I do annually with marine gas engines, outboard or inboard. Its cheap (SeaFoam is $5/bottle at NAPA) and keeps the entire fuel system clean, along with removing deposits on valves and in the cylinders. It won't make you any friends on the dock when you do it (the smoke produced is incredible as the carbon burns off!) but it absolutely works.