Naturally, this soon came to the attention of British Leyland, the corporate home of Rover and MG. They were a little embarrassed that Costello had been successful in doing what they had abandoned. They evaluated Costello’s GT V8 and then ordered their engineers to begin experimenting with the Rover V8 in the GT. At the same time, perhaps not surprisingly, Costello’s source of new V8s began to dry up, but the resourceful engineer was able to scrounge enough used ones for rebuilding to keep his MGB GT V8s going for two more years.

MG engineers modified the V8 as required to fit into the smaller space, including designing revised exhaust and intake manifolds that placed the twin SU carburetors at the rear of the engine. The fit under the GT hood was so tight that small circles had to be cut out of the hood’s insulating pad to accommodate the tops of the carburetors!

Power went through a four-speed all synchromesh manual transmission fitted with an electric overdrive that operated on fourth gear. This gave a long-legged overall gear ratio of 2.52:1, requiring the engine to turn a lazy 2,100 rpm at 96 km/h (60 mph). Suspension was the usual MGB A-arms with front coil springs, and leaf springs with solid axle at the rear. Steering was by rack-and-pinion.

BL introduced the MGB GT V8 in 1973, and the only external differences from the four-cylinder model were alloy wheels, larger tires and V8 badging. Performance of the 1,086 kg (2,400 lb) hatchback was sensational, as would be expected with the (SAE net) horsepower increased from 79 to 131; even more important, the torque was increased from 94 to 185 lb.-ft. Britain’s Motor magazine reported zero to 96 km/h (60 mph) in 7.7 seconds and top speed of 200 km/h (125 mph). While impressed with the outstanding performance, the testers felt the aging design lacked refinement.

The handling, style and dash of an English sports car wedded to smooth American V8 power would likely have enjoyed popularity in North America, but the GT V8 was not imported, because BL considered the cost of meeting safety and emissions legislation prohibitive. The MG GT V8 was manufactured from 1973 to 1976, with a total of 2,591 built. Production would no doubt have been higher except for a relatively high price, and a chassis that was becoming dated.

It was another example of combining American power with an English chassis in the tradition of cars like Hudson Railtons and Cadillac Allards. A few have reached North America.