Yip, that's why it's called a reverse bleed - you're letting the bubbles natural tendency to raise to your advantage...
I got a long hose, connected it to the bleed valve and ran it up the the top of the engine, poured [strikethrough]oil[/strikethrough] brake-fluid into it until it was bubble free (no use introducing more
air!), then connected the oil can. Might take a few tries to get it bubble free... Then after sucking out the old [strikethrough]oil[/strikethrough] brake-fluid in the master reservoir with a syringe, gave it 10 or so good pumps on the oil can to fill it up again (your number of pumps may differ), kept on doing this until both of the following were true:
- the [strikethrough]oil[/strikethrough] brake-fluid is clean
- there are zero bubbles popping up after a few good and vigorous pumps
Then did a few more iterations just for shits and giggles.
The final trick is disconnecting the hose from the bleed valve without dripping it all on your face, this was managed by putting clamping clips on the ends of the hose beforehand.
Some folk in an effort to cut out the syringe and save some fluid actually form a loop doing this by making the fluid from the master go directly back into the oil can, quite a nice idea, but if you're cleaning out old [strikethrough]oil[/strikethrough] brake-fluid best to rid the system of it. Make sure you take it off to a local garage that can take care of it in a slightly more environmentally aware fashion than dumping in the drain.