The first real band I was in, I played bass thru a Sunn Sorado & the guitarist played an LP thru a Sunn Sceptre, we were LOUD, & I thought he got a great tone with his amp. Got a chance to score a Sceptre off Ebay couple years ago, I found it impossible to overdrive at any level that I could stand to be in the room with. Took dirt pedals well, but eventually I came to realize the truth that so many here had tried to tell me, Sunns are really clean amps. If loud & clean is what you want, it's great, but most modern guitar tone calls for at least a little dirt, IMO.
As far as I know, all Sceptres were designed for 8 or 4 ohms, standard cab was the staggered 4X12 (altho I've read there were a couple other options as well).