Yes it can be done - but the crown thickness may be an issue.
FWIW, Phil or Bill @ http://bitsofitaly.com/services do this sort of work.
I've used them before many times.
If you give them a spare piston (like from a wrecker) they'll be able to tell you if it can be done or not.
Get someone to depress the pedal while you look at the Slave.
If the slave is moving a bit & looks ok, renew the MC. If that doesnt cure it, try the slave next.
Was it a nice consistant flow of fluid when you bled the system?
To quote Schedule 'B' of the NCR's in my CAMS manual:
Vehicles must have fitted an oil-trap container of at least 2ltrs for cars under 2000cc or
3ltrs for cars OVER 2000cc.
The general rule of thump I go buy is at least 2/3rds sump capacity.
This takes care of any instance whereby the engine may pump out the contents of it's sump.
Perhaps you should do your research before you post misleading info Stef...
I have the greeny coloured Por15 painted in my engine bay, that Lou applied before he sold me the car.
Apprears to have adhered well...
What do you want to know?