Lalla's in it. All of the living cast except Tom. As you Denis Carey died in the 80s, David Brierley is no longer with us, so he got John Leeson to voice K9. The gent playing the porter also died, but his scenes were all completed.
Sylvester isn't in his Shada, he got him to film visual footage for his Downtime, Search Out Science and Destiny Of The Doctors Special editions.
I got mixed up somewhere along the way. I remember hearing about McCoy doing an expansion to Downtime. I wasn't aware Levine was doing anything with Shada. And I agree that expanding Search Out Space is pointless.
He can't release them on his own, he did them on the hope the BBC would pick them (or at least Shada) up. He was behind getting the lost sequences of Planet Of Giants redone, and they will be an optional extra on the DVD later this year.
Now that one is a good move. I had no idea myself that there was a "missing episode" with that story, and as the final complete Hartnell story to see release, it's a cool bonus.
I'm interested in seeing what happens with Downtime, as I remember the original and adding the Doctor to it would be interesting. (I want to see it in circulation again anyway because it features Sarah Jane and the Brigadier). If I had to hazard a guess as to where it might fit into the BBC releases, there was a report from one of the conventions a few months ago that commentary had been recorded for a planned DVD release of the incomplete The Ice Warriors. As Downtime focuses on what happened to Victoria after her travels with the Doctor, adding it to a release of that story would make sense.
Personally, I'd love to see BBC Video pick up the rights to do a "fan productions" box set and get things like Shakedown, Downtime, the Auton trilogy and Mindgame and the like into wider circulation. They aren't everyone's cup of tea, but they deserve recognition for keeping the Whoniverse alive during those dark years when the show was off the air. They also acted as a valuable training ground for many writers and other personnel (Mark Gatiss and Nick Briggs, to name only two) who went on to work on the TV series and for Big Finish and other shows as well. (That said, reportedly the PROBE spin-off series starring Caroline John as Liz Shaw and co-starring Louise Jameson, Peter Davison, Sylvester McCoy, I think Pertwee in one episode, and others, is being reissued on DVD around this time, probably only in the UK.)