Chasing a firm brake pedal, What next? Options

[robkammer]

Teeners: It's been over two years since our 74 BB arrived. A Caliper blew out as it came off the transporter in 12 degree temps. Really no surprise as the PPI pointed out a leaky caliper. So I did what I thought would be appropriate for this little beauty, I sent all of the hard bits out, calipers and regulator, to a widely recognized firm for 'restoration'. Put in a new EZ master from 914. And all should have been fine. But, even now, after 1800 miles, a second set of calipers from the 'restorer', a new ATE MC from the restorer. ( I threw out the EZ MC). I still have squishy pedal.
I do not suspect the pedal box area as the car has absolutely no rust.
I just rebuilt the 'restored' front calipers with new square cuts from AA, took out the springy metal pieces that are supposed to keep the pistons from rotating, and the pedal is much better. I have about 50 miles on this but after bleeding it again the bleeders were leaking and I put it back on the lift. ( I was told: maybe: we left the calipers in the acid too long)
So: Now that the pedal seems like I might be on my way to GOOD braking, I can hear the pressure regulator knocking when I press the pedal, at a standstill, in the shop. Is this normal and to be expected? Note: During attempts to bed the brakes and get them working, I was only ever to lock up the rears, and it was really difficult to do. ( difficult may not be accurate, violent might be more appropriate)
The newly rebuilt calipers seem fine, just like the calipers in my 911's that I rebuilt.
As for bleeding, I've done it every way known to man. And some new ones too. Just picked up a 6th quart of Super 4. $26.00!!! A fifth of Weller was only $23!.
I'm really frustrated with this little car. Any input will be appreciated.

I'm thinking of putting in a Tee in place of the regulator, just for testing. If anyone has a Tee that they would be willing to let me borrow, I would be willing pick up all of the shipping just so I don't have to mess with the fab work.
Thanks,

[peteinjp]

I can only lock up the fronts on my car. Generally speaking the fronts should lock before the rear to keep the front- in front. Imagine needing to brake hard in a corner for some unforeseen reason and the rears lock...

If the rears are locking I don't think a T will be making any difference as the regulator is supposed to limit pressure to the rear specifically to keep them from locking first. I suppose it wouldn't hurt as a temporary problem solving effort and not a bad idea to pull the regulator apart and check its condition.

Sounds to me as if either your front circuit is not doing its job or the regulator is not working correctly.