......but there probably won't be any point unless you can re-bore the cylinder as well. You will need a new (oversize) piston and ring set to match the re-bored cylinder. Forget it and fit a replacement engine - it will be cheaper anyway.
If you want to tackle it as an 'I can do it' exercise, check out the price of the parts - www.briggsbits.co.uk if Briggs & Stratton, phil_saunders(a)bigfoot.com if Tecumseh.
The best compromise would be a new short engine, and your existing head, flywheel, carb and cowling.
phil_saunders(a)bigfoot.com
Phil Saunders
April 2009