1st try at converting a recipe. How's this look?

I'm trying to convert this recipe to all grain.

Chocolate Bar Imperial Stout

Original recipe:

OG: 1.099

Grain:

9.9 Lbs Light Malt extract. (Not sure if it's LME or DME?)
2.0 Lbs Brown Sugar
1.0 Lbs American Chocolate
12 oz American Black patent
12 oz Roasted barley
08 oz Flaked barley
05 oz Rolled oats (Quick oats)

Hops:

3.0 oz Cascade (6.4%) :90min
1.5 oz Willamette (4.1%) :45 min
1.0 oz Cascade (5.3%) :45 min
1.0 oz Willamette (4.6%) :15 min

Yeast:

White labs WLP 007


28 oz (800g) of Lindt Swiss 85% Cocoa Bars melted and added to boil for the last 10 min.



I used beercalculus.com to try and figure out an all grain version.

Here's the grain bill I've come up with:

Grain

14 lbs American 2row
01 lbs American Chocolate
12 ozs American black patent
12 ozs Roasted Barley
08 ozs Flaked barley
05 oz Quick oats
02 lbs. of Brown sugar


Questions:

1. Does that look Ok?

2. Also, do you guys have any advice for Mash times/temps?

3. I'm concerned with adding the Cocoa bars. I've heard this might mess up the head on the beer. I emailed the guy who originally posted the recipe and he said it wasn't a problem. You guys ever use cocoa bars?

1. yep, just replace the extract with base malt

2. depends how you like it. i would mash low at about 150°F to keep it nice and fermentable and dry.

3. i've used chocolate a couple times and never had problems with head retention, and i've used them in the secondary.