I would beat down that little lump that sticks up on the starter gear plate. then file the nicks a bit & check to see if it fits without rubbing (I think it will) then I would install it & go.
I would consider smoothing out the alu fin thing on the case if there is a crack in it (kinda looks like) but even a total removal should cause no harm
edit: if the bottom end is apart, I don't put it back together untill the top is on.... reason is that is you drop something in the hole up top, guess where it ends up. this can happen when checking valves for instance (how do I know this). thats the reason I Locktite the little dowel bushings into the head (the ones on the cam caps)
if the bottom is already assembled & the head is off you can let the chain fall in the hole while doing the work & pick it up with a magnet later... done this many times.
Beezer screwed with this post 01-26-2013 at 02:42 PM