It would take a custom transmission to make a B, D, or H series motor work in a rear wheel drive. Since the honda motor spins in counter clockwise if you attached say a RWD transmission to a honda motor, you would have 4 or 5 reverse gears and one forward gear. An MG would be a hard car to fit a honda motor into as honda motors sit transversly, and MG motor sit longitudily. MGs are meant to RWD, so they are rahter narrow, so it would a real tight squeeze to fit a transversely mounted honda motor in there. If any honda motor should be mounted in an MG it should be the RWD F20C or F22C from the S2000. Although to fit that motor in an MG you would probably have to cut a hole in the hood and the head would have to stick out, as that is a tall motor.
If you look at the crank pulley end of Honda 4 cylinder engines through model year 2000, the engine does spin counterclockwise. It's not a problem for swaps into other makes of cars if you use the Honda transmission. If you want to use the original car's transmission (your MG), then it won't work.
The K series engines in the RSX, TSX and S2000 (F20C) spin clockwise. You can use those in your MG without any problems. I think (not 100% sure) the old VW bus transmission is set up to run with a CCW engine too, so that might be something to look at.