Easiest swap for the 2001 Civic Ex,would be a 2001 Civic Ex engine. 
Next to that would be the K swap...any model/year K20/k24 would fit in the engine bay extremely snug,but Hasport makes engine mount kits for the swap.
Check out www.importautosalvage.com
Next to that would be the K swap...any model/year K20/k24 would fit in the engine bay extremely snug,but Hasport makes engine mount kits for the swap.
Check out www.importautosalvage.com