Easy there!

The carbs throat or "runner" has a specific shape, length, diameter, etc. it's a venturi shape, that is responsible of pulling the fuel out of the needle/jet as air flows through it, if you just bore it out you'll have your share of problems at least from low to mid range.

You can obtain a fair amount of power just by timming the engine just like the XZ. Other than that you need to balance the crank, work up the squish band, do the usual reciprocating lightening and the all important flow mod.

BUT - if its your first time,and if its a new engine, do an old one fisrt for practice!!, I've seen many people wreck new engines and turn them into trash. Im not saying dont do it, go a head do your thing and learn your stuff thats prety cool, but dont youst throw away $150, before you do, get an old, working!, $40 used engine and do some port testing a bit at a time and see results. THEN wreck your new one with no excuses!!!

X