Brake Caliper Rebuild Question

I'm rebuilding the brake caliper on our CB360 and when I popped out the piston I found this. 

 

That's the worst of the pitting. I can feel it on my finger nail but it's slight. 
I should mention that the reason I'm doing this at all is because the brake blew out yesterday and dumped its fluid onto the rotor when I cranked on it. Uh oh. It's never worked well...
I'm hoping to hit the brake with some scotchbrite/copper wool and a new seal and pop it back together. We need the bike back in service ASAP. It can be made perfect later, I just need to know if it will work for a bit. 
Am I being stupid?

My concern would be that you may risk damaging the seal when putting the piston back in. At the very minimum I'd order a new piston and seal like, yesterday, and then very, very carefully try to clean up the piston and possibly even use a whetstone to clean up the corrosion.

tl;dr - get a new piston and seal, stat.

+1 on new piston. 

Places like Bike Bandit have stuff, but not knowing the year makes it tough. (for me)  Yeah, new seals, pistons if you can find them, but the pitting is moisture in the brake fluid eating the metal, clean regularly changed BF will be OK on that piston.  Get a very fine wet stone as Tim suggested.  If you use any copper wool; DON'T.  Too aggressive, use 0000 steel wool.

I just went through this with three Goldwing calipers and two Masters.  =~ (

Dan

$31 from these guys. 

Boxhead FTW. 

Thanks for the advice y'all. I've not been inside a caliper like this before so I had no reference for this. 
I may have found someone locally with parts so I can get this going tomorrow. If not I'll order a kit. It could use pads too. 
The front brake on these bikes is hilarious. I guess being a stainless disk the coefficient of friction is pitiful. It can only get better from here !