What do you have to spend? And how many miles are on each 318? any of them low miles? Just a warning, until you pop the engine apart you don't know what your getting into. You could pop it apart and get away with a crank polish and a re ring and bearing. or you might need to do lots of machine work. machine work is expensive.
To put things into perspective, I rebuilt a 318 shortblock and put 360 heads on it that i already had. I spent about $500 bucks including rings, all bearings, all gaskets, 2 cans of engine paint, 2 oil changes, 2 gallons unmixed antifreeze. pretty much everything to do a rebuild and drive it for 500 miles. I never set foot in the machine shop.
The other day I was with a friend at the machine shop and he was getting cylinders bored, they told him 35 bucks each cylinder to bore.
Hope this helps a bit to get an idea of what things cost. This is all costs within this year so they are very accurate.
