Ned,
I've owned many Bandmasters in my time, and wish from time to time I still did. 40 watt, no reverb black faced Bandmasters. I've also tried a number of speaker combo's and types with them. Strange you should ask this question because I just quoted some history in another thread, but here's the deal.
If you want that amp to really, really sound the balls, use a closed back cabinet and either a pair of JBL D120's ($$$$$300 - 400 ea.) or a pair of Weber "California" 12" clones with treated edges and aluminum dust cap ($90 ea. - Weber high power w/ Ceramic magnet).
The other choice is SINGLE a D130 15", which you can get on Ebay pretty cheap ($50).
If you can't find a Fender cabinet on Ebay, make sure you get one that is a duplicate, closed back, tilt legs, and knurled hold down bolts for the head.
My first Bandmaster was a 1965 pre CBS bought at Wurlitzer Music in Boston. I paid $120 for it with the dual 12" cabinet. I sold the head last year for $100 to a friend who had been begging me for it since we were kids. The cabinet was long gone, and 2 years later, 1967, I bought a Super Reverb and the Bandmaster became our vocal monitor which when ties to a Bogan worked pretty well.
DO NOT use 10" speakers with this amp.
http://www.vibroworld.com/parts/tech21.html#fendercabs http://harrisburg.backpage.com/MusicEquipForSale/_vintage_fe nder_bandmaster_cab_only_200/classifieds/ViewAd?oid=1288854
https://taweber.powweb.com/weber/ http://cgi.ebay.com/JBL-D120F-D120-VINTAGE-FENDER-TWIN-REVER B-ORANGE-BASKET_W0QQitemZ170309312782QQcmdZViewItemQQptZLH_D efaultDomain_0?hash=item170309312782&_trksid=p3286.c0.m1 4&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240% 3A1318%7C301%3A0%7C293%3A1%7C294%3A50
http://cgi.ebay.com/JBL-d-130f-vintage-speaker-guitar-or-bas s_W0QQitemZ250384875934QQcmdZViewItemQQptZGuitar_Amp_Accesso ries?hash=item250384875934&_trksid=p3286.c0.m14&_trk parms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C3 01%3A0%7C293%3A1%7C294%3A50