Dodge 440 ,miss firing

I just got back from the motorhome. as per compression test it was a chore to change the plugs as there isn't much room to fit much. There was a LOT of black stuff on the porcelain plus a lot of black on the metal part too. There were 6 plugs that had black on the porcelain. It ran much smoother. but I still have two problems one is that it stalls (always did after running a while) and there is oil that hits the manifold and smokes to high heaven. I tightened the valve cover bolts and there is a lot less smoke. but still present. I also have an exhaust leak as you can hear that sound. it is coming from the left front of the engine. It has two old electric fuel pumps that sound like they are dying. I changed the fuel filters. I wonder if the stalling is caused by the fuel pumps. It has a main and auxiliary tanks I installed a much older rebuilt Thermoquad It has less vacuum hose ports and stuff. but I just need to have it run 40 miles to get it home. then I can take the time to save up for a new Edelbrock carb and maybe really work on the engine. I would love to trade the engine in for a John Deere diesel and well that is a pipe dream but I would love to re power it with a diesel and a John Deere 4 cylinder is not much heavier than the 440 and it is sleeved. Well for now and probably the rest of my life I need to get this where i can trust it. Does it matter what year the carburetor is? for the 40 miles trip? the original was gummed up really bad and had a crack in the plastic housing. and this one i got was rebuilt a while ago This motorhome has cruise control and that diaphram is all rotted away and it is controlled by the vacuum lines off the carb? right? If so I am sure this older carburetor doesn't support cruise control.. I need to redo all of that once I get it home. But the black on the plugs are a bad thing? cause the porcelain on 6 of them were blackened. Oh,, the generator is an emerald 6.5 Onan.