First of all forget the 6.
MG tried it, and dropped as it ruined the cars handling with the added weight.
The orginal 4cyl is a great little engine, and has plenty of tuning potential on its own, other wise the buick based Rover V8 is an easy conversion, weighs less than the 4cyl, and as you can imagine has more than enough hp for what the MG chassis can handle.
If you stay with the orginal A series engine, then there is overdrive avliable for the g/box that gives you an effective 6 forward ratios.
The V8 is commonly found in Land Rovers, and Defenders, as well as old P5 and P6 Rovers.
The later the engine the more power it will have stock, but the more work will be required to get it into the car.
Forunatly since V8 versions were made by Rover, there are conversion parts easily avliable.
The second thing you need to do is get hold of your nearest MG car club, you will not find a better source of information and parts.
All the parts for the car are avliable, and its actualy possible to buy all the parts required to build a totaly new car.
A quick look in a classic car mag will give you ads for suppliers, or try these guys:
http://www.rimmerbros.co.uk/
And most importantly find a Haynes or similar workshop manual.
Need help, Dad and self are going to work on 77' MGB
