Leftover Grains (Frozen) for Stout. What percentage of base grains?

So I have the following grains (frozen) leftover from another recipe:

Pale Chocolate - .25 lbs
Midnight Wheat - .75 lbs
English Roasted Barley Malt - .75 lbs

for a total of 1.75 lbs.

So the idea is to use these grains plus base to get to whatever gravity it brings me to.  I'm thinking I'll end up with something resembling an Imperial Stout.

The questions I have are:

What percentage of base grains should I utilize?  I've seen anything between 70-80% for stouts.  My rationale is that since the specialty grains are frozen that I should probably lean towards the lower end for the base malt to get the most out of the frozen grains.

What base grain?  I've been using American 2-row to this point, and will probably use it unless someone suggests an alternative.

Should I include any other specialty grains or adjuncts?  Rice hulls?  Caramel?  Carapils for head retention?  Anything for body?

Any suggestions are appreciated.  This will be the fourth all grain I've done.

Thanks!

I try to stay as close as I can to the German Purity Laws and therefore, I also like to use ingredients indigenous to the particular region of the beer I'm brewing.  While I have never brewed a stout, I know that the style originates in Ireland and to the best of my knowledge, Ireland does not offer grains.  So, the Irish would procure their grains from the UK.  So, my suggestion for a base malt would be Marris Otter.  I have used this malt many-many times and I love it.  The malt is very consistent and very flavorful.

As far as recipes, whenever I'm stumped, I turn my attention to some of the great recipes found on the BeerSmith website, or Brew Your Own (BYO.COM) to name a few.  There is a wealth of information out there.

Two great books that contribute to almost every batch I brew now are "Brewing Classic Styles" and "Designing Great Beers".  Highly suggested.

One challenge I had when developing a Stout recipe was picking which one to go with.  The 2015 guidelines have a multitude of them listed:

http://www.bjcp.org/docs/2015_Guidelines_Beer.pdf

Irish, Irish Extra, Sweet, Oatmeal, Tropical, Foreign Extra, American, and (American) Imperial.  Interesting to note that the Foreign Extra is compared to a Russian Imperial, but Russian Imperial is not listed as its own style.  Huh.

BCS suggests 10% roasted barley and as I recall 5% chocolate malt.  The Stout I'm drinking right now (not imperial, more like an American Stout) also had 5% flaked barley for a bit of head retention.  You shouldn't need rice hulls for this one and I personally wouldn't suggest Caramel.

I see in the article linked below that BYO states "British pale ale malt or Pilsner malt has too much grainy and biscuit character for this style."  ... but I'm with Keller on this one.  I went with UK pale malt and am digging it.  I also love Marris Otter and this is the tweak that I'll make next time I brew it.

http://byo.com/hops/item/2341-american-stout-style-profile

Let us know how the recipe progresses!