Sort of a steam beer-critique

[NeilArge]

G'day all
I was planning to put down a steam beer soon but when I checked the hop supply saw that I didn't have any Northern Brewer hops left. I'm on a bit of a drive to reduce quantity and range of hops I have at the mo so thought that I would make up a hop bill with what I have. How does this look? Will the Northdown work as a later addition hop?
Cheers
ToG

Recipe: Lettin' off steam
Brewer: Neil
Asst Brewer: 
Style: California Common Beer
TYPE: All Grain
Taste: (35.0) 

Recipe Specifications
--------------------------
Batch Size: 22.00 L      
Boil Size: 25.18 L
Estimated OG: 1.055 SG
Estimated Color: 23.9 EBC
Estimated IBU: 38.1 IBU
Brewhouse Efficiency: 80.00 %
Boil Time: 60 Minutes

Ingredients:
------------
Amount        Item                                      Type         % or IBU      
3.60 kg       Pilsner (2 Row) Ger (3.9 EBC)             Grain        73.47 %       
0.68 kg       Vienna Malt (Weyermann) (5.9 EBC)         Grain        13.88 %       
0.45 kg       Munich, Light (Joe White) (17.7 EBC)      Grain        9.18 %        
0.11 kg       Special B Malt (354.6 EBC)                Grain        2.24 %        
0.06 kg       Chocolate Malt (Joe White) (750.6 EBC)    Grain        1.22 %        
15.00 gm      Magnum [14.00 %]  (60 min)                Hops         22.3 IBU      
40.00 gm      Northdown [7.50 %]  (15 min)              Hops         15.8 IBU      
28.30 gm      Mt. Hood [6.00 %]  (0 min)                Hops          -            
1.16 items    Whirlfloc Tablet (Boil 15.0 min)          Misc                       
4.00 gm       Calcium Chloride (Mash 60.0 min)          Misc                       
4.00 gm       Gypsum (Calcium Sulfate) (Mash 60.0 min)  Misc                       
1 Pkgs        California Lager (Wyeast Labs #2112) [StarYeast-Lager                


Mash Schedule: Single Infusion, Light Body
Total Grain Weight: 4.90 kg
----------------------------
Single Infusion, Light Body
Step Time     Name               Description                         Step Temp     
75 min        Mash In            Add 12.78 L of water at 71.9 C      65.6 C        
10 min        Mash Out           Add 8.18 L of water at 93.5 C       75.6 C