yay you posted a peugeot 102 porting guide haha.
get a tomos or polini reed plate. bolts right up. wayyyyy better.
i would go to town on that exhaust port, raise it like 2mm, and widen it by about 2mm (1 on either side) and see what that does. you can also advance the timing by a couple degrees.
and of course slap on a puch ignition coil to make it reliable.