There should be no dremeling needed on the bulkhead at all...
The only work needed is the chassis milling to allow the motor to go further in.. and the top desk filing down for the same purpose.
Also you must be hitting things pretty hard to break a topdeck... i've gave mine some pretty decent whacks (including off the track via punching it because it wouldn't handle on track.. ouch.. carbon fibre is sharp) and it's not broke...