If that back end wall cuts off air coming from the engine during travel. It would need to seal to the hood and block over to the battery at a minimum. Obviously when the car is stationary there will be heat creep / saturation.
The stock is good, but hard to get these days, as you bought the car second hand your not likely to have access to it. These have larger intakes than the other models of the same year, so don't look to those.
If you want to keep the same basic setup you have and get a little more out of it, you could get an extension pipe to relocate the filter in the fender. Then you only need to ensure you don't go through large puddles otherwise have to further cover the filter to prevent water being sucked in. Ensuring the fender wheel well plastic guard is in place will do most of the work.
Cool you got it in there and hope all works well!