these have been out for a while:
S&M models has created resin conversion sets in 1/144:
- VC-10 R.1 (reconnaisance variant)
- VC-10 poffler (Skybolt missile carrier)
- VC-10 MR.1 maritime reconnaisance aircraft to OR.381
- VC-10 MR.1 scheme B
The Poffler and MR scheme B can be found in 'Vickers VC10: AEW, Pofflers and other unbuilt variants' by Chris Gibson
the MR for OR.381 is described in 'Nimrod's Genesis: RAF maritime patrol projects and weapons since 1945' by Chris Gibson
the R.1 is described in 'Listening In: RAF electronic intelligence gathering since 1945' by Dave Forster and Chris Gibson
These fit the Airfix kit, you can probably use them on the Roden kit as well.
I've got the R.1 conversion set, I'll try and make some photos.