really, if you are asking these questions, the best thing you can do is start with a good stock rebuild, find a used stock crank in good condition, and start by doing the basic speed mods
proma GP pipe
remove the head gasket/ high compression head
used OEM bing 14 (see ken's jetting recommend but 64 main instead)
first thing you'll do is learn to set the timing and get good at that
next you can play with carb tuning
then you can see how modifying the timing to advance more or retard does for your performance
then you can start taking off the cylinder and porting it a tiny bit at a time and see how that changes
then you can mutz with the gearing and see how that changes
if you do that for an entire riding season and pretend that performance parts don't even exist, you will know more than 90% of the dummies who post on here with bad-running kitted bikes and blown up shit. a lot of us that have been in this for years started doing exactly this. You learn so much more about your bike and in the end you'll have something that does an easy 45 with great takeoff and blasts a lot of badly built kitted bikes.
the puch manual is really well written as well, its worth reading cover to cover. print a copy and put it by your shitter.