I own a Victoria 518 tweed champ, which comes with a 4 ohm extra large (tweed super) transformer capable of taking both 6V6 and 6L6 tubes without rebiasing. I would love to build a 60's Vibro Champ replica, but with a transformer (1) big enough to handle both 6V6 and 6L6 tubes without rebiasing; and (2) 8 ohms for easier use as a head with extention speakers/cabinets. Is that possible? What transformer would you recommend? Would such a transformer require any other changes in the circuit? This would be my first build, so I just don't know this stuff.