Series 2 Brake Problem

Just finished a rebuild of my SWB 1963 2A that we have had since 1965 and now debugging the thing.
The other day I found that although when pushing down on the footbrake all the wheels brake okay, I can push harder and the brake pedal goes to the floor. Today I replaced the master cylinder with a new TRW/Lucas one, performed a full all wheel brake bleed, but still have the same symptoms. I never had this before the rebuild, no air in the system, is this a common thing? The only thing that happens wheen pushing to the extreme is that one of the new front hoses has a very slight twitch; faulty hose or ignore it?
Any ideas are most welcome.
Best Regards
Mike

If the flexi hoses are old, theymay be perished inside and swelling as the pedal is pushed. It may be worth replacing all of them if you have any doubts.

Col

Have you got correct free play at the master cylinder with pedal fully up pushrod should have a couple of mm free play.
If that's ok it is likely you still have air in the system assuming your not loosing any fluid.
If you stamp on the brakes a few times it will break up any large bubbles and allow you to bleed the small ones out.
Are they original shoes and drums?

Have you got the right adjustment on the shoes?

Next time you bleed, lift the front up 4 or 6inch they bleed a lot easier