Thanks for the links guys. Very helpful reading.
I think I'll try and keep it as 'book' as possible but with obvious alterations for chassis strength and mounting the engine. This isnt only my first 'build from tubes', its my first build - I believe in aiming high then at least you achieve something.
I'm not scared of working metal and have used an Arc welder many times for welding box section steel, although my first practice with a MIG last night was less than satisfactory.