Seanod this may interest you:
Where's where in Dublin: a directory of historic locations, 1913-1923 : ...
http://www.rootschat.com/links/07lf/ page 6: 55 Amiens Street ...
page 55: ... On 21st May 1921 a meeting was held here to finalize the plans to burn the Custom House. In attendance were Michael Collins, Sean Dowling, Richard Mulcahy, Ginger O'Connell and Oscar Traynor.
Hi Linda, Thanks for that. I thought this was another version of the book I've mentioned before, Dublin in Rebellion, but it doesn't give the same information. The Dublin in Rebellion book says that 55 Amiens street was the home of Seán Doyle, who was killed at the CH, but there is no mention of the meeting. I'll have to get that book.

This was posted in Dec. by Linda
I am the author of both books, and would be happy to answer questions if I can - though the info on this site is marvellous.
Also I have a regular spot on Talking History on Newstalk and the May segment is to include the burning of the Custom House. The segment is the first Sunday every month, and starts about 8:45 pm.