PortaPro + Sony DR-S4 - modding advice!

[discombobulation]

So I found an old DR-S4 headphone with the leather headband and pads surprisingly supple after years of sitting in an attic, and thought that it would be a good opportunity to rehouse my PortaPro drivers.
 

 
 
As you can see, the drivers are pretty small in the enclosure, but I am keen to try the PortaPros in a closed cup for the added isolation.
 
Does anyone have any tips in terms of padding/acoustics etc in the cup? There is plenty of space in the cup with the small PortaPro drivers, so I was thinking about some foam for damping etc, but this is my first DIY mod so suggestions would be appreciated!

 

[Marks847]

At first You need to place small size Koss into bigger flat round plate with multiple holes in the center fixed with glue.
Next step to fix this plate exactly in old place instead of SONYs capsules.
Some synthepone material over the new capsules for dumping will be good for solving resonanse problem.
The sound will be not so opened but better in wide range of frquency. The total wight will be lower.

 

[WIFIBIS]

Por favor me podrias decir como los has desarmado, necesito lubricar los potenciometros que hacen ruido.
Please you can indicate me since you them have disarmed, I need to lubricate the dimmers that do noise