Owners of Triumph TRs, MGs used to go through gearboxes, but I don't think that was related to horsepower. :wink: Actually, there were a couple of tries made to give the MGB some power, there was the MGC which was the MGB with the 3 liter I6 from the Austin Healey. Then there was the 1972-76 MGB GT V8, which used the 3.5 liter aluminum V8 GM sold to Rover at the end of the 1960s, same engine used in the Truimph TR8, Land Rover Discovery. The MGB GT V8 did 0-60 in 7.1 seconds but due to the fuel crisis and slow sales it wasn't sold in America.
One problem with the two overdrive ratios in the BW T56 is that they are good for economy, but the LS1 5.7 doesn't have as much low down torque as the LT1, and you have to change down on slight gradients because 6th is so tall.
Pontiac's V8s always used to be known for good torque.