I know that in the US most of you want to have "thunder" drag times...
But since youŽve got a English car, try making a rally car rather than drag.
I have more fun in a good twisty tarmac road than smoking tires through a stop light....
Anyway...
Get yourself a good 1275cc A+ engine. Those that came with MG Metro, Austin Metro, Allegro, Montego and so on....
I could go on and on about tuning that engine, but IŽll stick to the basic 1st stage to be done.
Unless you want to race, start with a good intake manifold (the metro 1.3 is already a good one...) with the HIF44 SU carb, correct needle and a good K&N filter w/ram pipes.
A stainless steel LCB (long Center branch) type exhaust manifold, with a 2'' link and end pipe (RC40 type backbox).
Add a Oil cooler and consider a change to a electrical radiator rather than that mechanical stock one (some experts say 5 hp gain) Late cooper (+90) ones are ideal for this.
A good coil. (Lucas Sport is just fine)
With these changes, and considering you got a MG Metro engine (72hp @ wheels), expect around 80 hp.
As you can see, by just making it "breathe" and work better youŽll get good gains.
Anything else, just ask!
By the way, I own a 1971 Morris Mini Clubman.