Voiceprint seem to be releasing a lot of Daevid Allen stuff at the mo - including 2 late 70's/early 80's usa lives very soon - so i guess it'll be via them. Otherwise, check out the Gong web site www.planetgong.co.uk.
I used to have the GAS tape of those recordings (from 1966?) called Tape Works. It was pretty interesting. I think some of these recordings were added onto the Death Of Rock cd - tho i might be wrong.