How much did you leave on your motor plate when you trimmed it down? I have my pattern at this stage right now, I had more on the outer edges as when I finish off my cage I'd like to attach a couple more tabs from the forward bars to the plate, then trimmed it a bit more.
I think I should still be able to add the extra attachment point if I cut it like this, if you run a motor plate please post some pictures of how you did yours.