Will a 2 ton heat pump cool a 3 car garage in arizona ok?

I have a 609 sq. ft. garage with a 10' ceiling, the garage panels are insulated and all 3 walls , but not the lid. What cooling issues might I run into and would a larger unit be more cost effective. I have a Lennox 13HPD-024 or an Aire-Flo 2HP13B24p...which is better for this? Thanks!