Need information on front and rear master cylinder kits for my 01 EC 300
 

When I first got the bike, the brakes wouldn't lock up at all. I bled the brakes a lot. That made it a little better. The pads were pretty much gone, so I've got new pads, and bled the brakes some more and they're both pretty spongy. The front and rear are both Nissin masters but I don't know which rebuild kits to order for them. The oil that came out was brown, so I'm sure there is some damage to the internal seals.

What is the indicator that the brake calipers themselves need to be rebuilt? They don't leak, but could this also be a potential source of the spongy-ness?

I'm also strongly considering an entirely new clutch master, since AJP is kind of floating between existing and not existing as a company. The flimsy sheet metal perch clamp is also deteriorating and a replacement is about 40 bucks shipped! Does anyone have any experience or recommendations for a replacement?