ok im gonna try to break this down for you..
1)boring is NOT necessary unless you need to rebuild. it wont give you anymore power by boring to the next size, so scrap that idea.
2)lose the boost bottle. it does nothing for you and gets in the way. go back to stock crossover tube.
3)i would run 33mm pwk carbs. they are good size for stock stroke and some porting all the way up to 4mm cub motors. ive seen 4mm motors run hard with them. they are a good investment and youll save money in the long run if you ever decide to build a big motor.
4)timing plates are great add-ons. increase timing will increase performance, but you need to bump up the octane in your fuel.
5)i would skip the shaved head and go for a NOSS head. better cooling and you can change your compression ratio. doing this in combination with your timing plate will make it worthwhile to run race fuel. you can probably get away with running a 50/50 mix of pump gas/110 or 112 octane.
6)which toomeys you have? T5 or T6?
7)the rest of your mods sound pretty good. i would check more into your porting and decide what youre gonna do there before you decide on pipes and other intakes.
hope this helps. hollar with any questions..