Severe Cropping Improvement Strategies

I have a photo that I took of a big horn sheep that I like.

I took it using a Canon T2i and 55-250 lens.

Unfortunately it's quite far away and the sheep is barely noticible in the image.

When I crop it the quality obviously drops way off.

I'm not looking to make it perfect but I'd like to improve it as much as possible.

I'm looking for some strategies to try.

One thin I did that helped some. I created a duplicate layer. I sharpenned the top layer using unsharp mask (app. 250, .7, 0). Then I created a mask and brout back the unsharpenned part of the image that didn't include the sheep. I did that so that the whole image didn't have a shrpenned look. That helped but I'd like to try other approaches.

I have Phtoshop CS5 Extended.

Thanks.