MG Car Repair: engine uprades, conversion kits, speed unit

Question
I'm looking to rebuild my 1980 B engine and was wondering what upgrades can be done to increase horsepower?  Also, is it worthwhile upgradng to an overdrive trans, or is it better to use a modern 5 or 6 speed unit? I've seen overdrive conversion kits on the web, but have not heard any feedback on them. Do you have any experience with this?

Answer
Hi Jeffrey,
The "B" gearbox with an overdrive unit is a very good unit and as long as it is installed correctly, it makes the car useable on US expressways and is still a great back country road car.
There are many things to raise the HP of the engine but keep in mind that as you increase the power you also increase the load on everything. If I had an 80 "B" the only thing I would do to it would be find an older "B" intake and exhaust manifold and a pair of SU carbs. This will only increase performance a little but in the correct RPM range and make it closer to the 67 and earlier "B"s.
Howard