Scag Walk Behind...Front Caster Wheels

I recently purchased an older Scag Advantage 48" walk behind. Its in great shape except for the front wheels. One is a flat free wheel that is heavily worn /torn on the edge and obviously does not have a valve stem. . The other is a tubeless tire with a valve stem in the hub. Both are 11x4 tires.
I would like to do this as inexpensively as possible. I could just put another tubeless on but I would have to purchase the hub along with it. I could put another flat free on but again... the hub/tire set is pretty pricey. 
Any suggestions are appreciated. 
Finally... there is a guy nearby selling a zero turn scag for parts. It has 13" front caster wheels. Would these wheels work on my 48' walk behind? If so, would it effect the leveling of the deck/cut?