I would split your cases and see if there is any other damage that was done first so you can gauge your budget. If your crank is toast and your going to go with a 4 mil you might as well get a 421 driveline setup or cub, serval, etc whatever your riding style demands are. But either way, doesn't matter with what option you choose, your gunna have to learn to tune the bike with any setup you get. Also, you CAN run anything you want with the setup (fmfs, stock carbs), most people don't and it just wont be optimal and there will be more power to be had for sure.
btw if u want the 421 setup with better pipes and carbs your budget is gunna have to be more than 1500
crank- 450
top end- 800 to 900
pipes- 550 to 675
carbs- 350
filters- 80
adds up quick