I don't think it will crash your world if it's in a chest: stuff in a chest is only accesed when opening the chest. It's only those placed somewhere in the world nearby the place you crash, that you have to get rid of. Just select a big area in mcedit and replace all "'unused brush" with air. Or you can also open the world in 1.4.7 and go bunch all dead bushes. Make backups if you're afraid to delete your world.
Drev, you could try to mcedit "(unused) shrub" out of your map and see if that fixes it. Hopefully you have the same issue as me because else I don't think they have enough details yet to fix your issue.
I did some testing with mcedit: removing certain blocks out of the area and check if that fixes it. Found it! At least for me, the issue was "(Unused) shrub" (as called in mcedit), item ID 31:0. The tall grass version of Dead bush.
Aw... That's bad news 😞. Should have taken a backup and not play around with mcedit if you don't know what you're doing I guess. I'm sorry for suggesting it. Does it still crash though?