1.00 KG Pale 2 Row Malt
1.00 KG Munich Malt
0.30 KG Caramunich
0.20 KG Chocolate Malt
3.00 KG Liquid Light Malt Extract
Hallertauer or Tettnanger Hops to 25 IBU\'s
15 Gm SAAZ
IMHO you need more Munich Malt - Bocks need this malt and you should make the Munich Malt the major contributor to your grist bill. As Jayse and Ken (edit: and JM!) suggest, add more munich and I would drop some of the LME - I would leave the pale malt in to ensure that you have plenty of diastatic power in the mash although the munich malt should be fine anyway. If you want to go really full on, ditch the malt extract and replace with an equivalent quantity (points per kilo per litre) of munich malt. Traditional Bocks use plenty of Munich Malt and have OG's of 1.064 - 1.072 (Source: BJCP).
If you must
use crystal malts, then the Choc malt will give a roasted complexity and you need to be sure that you want that sort of strong finish to your bock - 200g is fine - no more or you are going expresso with the beer!
You might prefer Caramunich - but its also worth considering using some Crystal malt in lieu of the Caramunich (once again, if you have to use specialty grains). I'm not so sure that the caramunich is going to stand out in amongst a fair bit of Munich - if you keep to only 1kg of Munich, then fine, go for the Caramunich, but if you up the Munich malt, you might want to dial down the Caramunich. (Its not a hard and fast rule, its just my preference - I'm sure others will suggest otherwise and recommend heaps of crystal malt - thats the fun part of making your own beer!)
34/70 is fine - or get some munich or bohemian lager liquid yeast. I'm about to do a bock using #2124 based on a recommendation given by a Wyeast guru in a "Brewing Techniques" article on German Lagers. His recommendation was based on the temperature tolerance and attenuation qualities of the #2124 strain.
Personally, I would bitter with Northern Brewer and then do the aroma and flavouring additions with Hallertau or Tettnanger. I plan on using about 25g of Northern Brewer - I don't want high IBUs for a Bock - its out of style.