Currently I have ubuntu 32bit on a 100gb partition,
For some odd reason I can't extend the partition if though I have available space.

Anyway I want to reinstall ubuntu with 64bit in a bigger partition(250gb)

Would it be possible to do it this way to avoid breaking mbr:

1. Installing ubuntu on other partition
2. deleting previous install of ubuntu and removing partition to extend new ubuntu install.

Would this overwrite the grub2 and allow me to boot both into windows and ubuntu?