1971 dart and 1969 merc cyclone

As a true Ford guy(who just happens to really like A-body Mopars),I can say that what SGB stated first is 100% fact.He never stated that ALL 351W have big plugs...just that 351C have small plugs.You may have seen a Windsor with small plugs,but you will never see a Cleveland with big plugs.Also 70-74 model year cars are the ONLY Ford products that came with a true Cleveland...period.A 1969 Mustang w/ a 351C had a motor swap.Its an easy swap because the W and C share the same bellhousing pattern,so its not uncommon at all.
As far as not caring if its a C or W,you should really find out.You may not care,but whoever buys it most likely will.The C is like the ugly duckling of Ford motors.Its a diamond to some and a boat anchor to others.Im a Cleveland guy who has almost no interest in a Windsor car,but small-block guys have no interest in a Cleveland.
Sorry to clog up your Mopar board with Ford ramblings,but Im just trying to get you some info so you can list it right and sell it quicker.That car should sell pretty fast if you list it right.....and maybe not on a Mopar Forum ;)