With my bike off the road and waiting for bits I got bored and bought myself a very cheap 1986 FZ750, its as old as me

Anyway, I took off the calipers and gave them a good clean. However on one of the calipers the bleed nipple was solid. I soaked it for a few hours with lashings of plusgas. I rounded the nipple. I then tried to use an extractor and the inevitable happened, it snapped. (yes I have read all the recent posts about removing studs, but my eagerness told me to go get stuck in with the tools I had).
I then filed it down so I had two flat surfaces, and sheared it flush with the caliper, nice.
Next step was to drill a bit more and try to use an extractor. FAIL.
I didnt drill that far into the nipple so I assume its still sealed. If it is can I just use one of these instead? click
I'd imagine bleeding could be a bit tricky. Can I get them local? I'm not looking for perfection here just something that works.
I've seen a few calipers on fleebay, but they look a bit rough compared to the ones on the bike and I could just end up with the same problem. Any advice would be much appreciated.