Hello,
From experience, if you try to modify a well packed box, then sooner or later you may find that something doesn't work quite right.
Vagrant core can provision VMs using Shell, Puppet, Chef and Ansible, so if you feel confortable with any of those, you may look into create a provision script that take an standard Linux of your choice and install all what you required.
The advantage of this, is that later, you can use the same provision with a different tool, like packer and cfreate your own box that match what require.
I understand that its time consuming and you may be in a rush, so I think the quickest is ask to the people who created that DrupalVM if they will allow other versions.
Most of the installed components came in the base box, I don't expect they install those components when you do vagrant up.
Thanks
Alvaro.