Still HEAVY brakes issues on a buddy's mine 73

[Nacho-RT74]

Damn... a Friend of mine hasn't had good brakes practically on his entire life... maybe just for a year or so. Several master cilinders and still problems.

-We have bleeded brakes hundreds of times and no air.
-Gravity bleed once, changing everything ( new pistons and seals ) and got perfect brakes for just one weekend or so and WOW... WAS SOMEKIND OF MERCEDES BRAKING LOL.... like a 4 disc setup. one touch and blocked brakes. then once and again allmost no brakes.
-He has had same issue than I have had three times on a year. Emptied front deposit and overflowed rear deposit on MC. HEY... NEW PISTONS AND SEALS, ON AN ALSO NEW ( ONE WEEK ) MC as stated above. Aparently I fixed changing pistons seals about a month ago with twice on a row same problem, even I got the same issue with new MC about a year ago and problem fixed alone , but this time with my buddy's car problem is still there.
-No visible leaks anywhere.

On a brakes shop, they ended drilling the MC wall between both depostit to keep them full... ok, nice now he will never get emptied front deposit, but that doesn't mean will have brakes.

They told that probably damaged distribution block... Is a posibility ? we changed once the DB for an used one that my car had that I just changed making test on my car once I got problem looong time ago ( not the same ), but as far I know was perfect, since my problem on those days really was MC.

Please, opinions.

If you didn't understand the problem because I didn't explained good, just ask me for some detail and I'll answer.