Just to fuel the fire a bit more , I have personally seen some MGBs with both V-8 power
and Mazda rotary power . Can you say GRRRRRRR !?!?!? I have seen one or two 2 liter (overbored) MGB powerplants also . Lots of torque to be had there . I guess you could throw a 2.3 liter Pinto engine/trans into a "B" , but then while you're at it , why not do a 2.3 T-Bird Turbo Coupe driveline

!?
If I had 20 grand burning a hole in my pocket , I'd build a Birkin kit (Lotus 7) .
~~~~~~~~~~~~~~Allen