Besides the dropped battery, RHD cars would seem to need a flat firewall so the right seat can go back far enough to be comfortable driving. You can easily do this by reversing the motor mounts side to side and bending a shallow 'S' in the ZF tabs. This moves the whole engine back about 0.8". Stock wiring, plumbing and the gearshift rod all have this much adjustment without complication. Then you can change the way a stock alternator in a stock bracket mounts and drive it from the unused inner sheave on the A/C pulley, which removes another 1" of engine length and makes only the water pump & pulley the source of any remaining protrusion. Cut that part of the steel firewall door away that's no longer needed, redo the bubble upholstery and most people in the right seat will NOT be able to reach the front firewall with their toes.