I would definitely split that case if the engines already out the extra few hours work could save a lot of money in the long run if there is still pieces down there you could break a inner case.
If your considering painting your frame there's a lot of work involved, I stripped mine and painted it white, I spent a day rubbing it down and after two days at the track it was all chipped, that was using primer then rubing it and then using 2k car paint.
I would consider powder coating it or if you do paint it use frame( a thicker version of Sellotape) it's basically a clear tape that goes over the paint to protect it that you can hardly notice, it lasts me 2 mx races