Note that Richard has now released an experimental version of BBCSDL for 64 bit Linux, so it might be worth giving it a whirl. Look at the bottom of the SDL page (you can get to it from the "home" breadcrumb above), or the link is here:
http://www.rtr.myzen.co.uk/bbclinux64.zip
I'm sure Richard would be keen to get any feedback on how well it works - and please post a comment on it here, too!
Best wishes.
D