Amp head & Cab Q!

Hey, So I recently acquired a 1975 Fender Bassman 100 Head with the 4x12 "inverted pyramid" cab. The setup sound amazing, and is built really well. Needless to say I'm in love with this amp. I'm using it for guitar only. My focus however is that the 4x12 cab is a real pain in the back side for gigging with, as it only JUST fits in my car, and even then often requires manoeuvring up and down large staircases. So I've decided to look into purchasing a 2x12 cab, but I'm endlessly lost with all the 'ohm' and 'watts' mumbo-jumbo. I'm considering the Fender Supersonic 2x12 ( http://www.fender.com.au/amplification/guitaramps/pro_supersonic_212_encl.php ) or the Bandmaster 2x12 ( http://www.fender.com.au/amplification/guitaramps/vinmod_bandmastervm212cab.php ). Will either of these cabs suit/work? I just don't want to blow/damage anything. The Bassman head reads "TOTAL LOAD 4 OHMS".