TM Recoil and UBR stock

[Cojack]

Afternoon guys and gals...

Really interested in fitting a UBR stock to a Marui recoil series AEG...However, I'm aware the UBR has a special stock tube provided to fitting to a standard AEG.

Obviously, with the recoil series - the recoil unit is located in the stock tube...soooo

Does anybody know what needs to be customised in order to fit one of these to the AEG in question?

Any help will be much appreciated.

Thanks

Jack