The differnece between a 413 and a samurai is the sammy has a wider axle and different ratios, I believe the sammy was the later version of the 413, it also has hand brake on the rear drum and a few extra creature comforts.
Don't know how hard it is to fit a pug engine but the 1.6 8v Vit in a 413 fits like a glove and is well worth doing the extra power is great you can even burn off those little chavs in their 1.1 saxos.
