I have a quick question, is there any quick way to tell if a pair of heads are 351-Cleveland heads? Thanks...

Well yea. they're freakin HUGE.

They'll have canted valves.. The intake and exuast aren't in the same angles.

Other than that, post up the casting numbers or get a book with them and take it with ya.

Pictures... I like pictures...

The Cleveland valve covers are more angular, and have a raised section were the hoses enter. The Windsor is more rounded and flat the whole length.
http://webpages.charter.net/w01845730/pictures/covers.JPG

The C has staggered valves, while the W is inline. Also note the "4" on the upper left corner of the C. This is a 4 barrel head with bigger ports and valves. The 2 barel head has a "2" cast there.
http://webpages.charter.net/w01845730/pictures/cantvalves.JPG

Intake ports. The W is an early head which has bigger ports than the 77 and later, which are 302 size. Still no match for the C though. 2 barrel C are less dramatic, but still bigger than a W.
http://webpages.charter.net/w01845730/pictures/intake.JPG
Exhaust; Windsors are puny.
http://webpages.charter.net/w01845730/pictures/exhaust.JPG

Combustion chambers; These are closed chamber, many 4 barrel, and all American 2 barrel are open chamber, fully round with no quench area. Only the Australian 302 Cleveland had 2 barrel ports with closed shambers.
http://webpages.charter.net/w01845730/pictures/combchamber.JPG