Imperial rye stout - recipe critique

Here is a partial mash recipe I'm trying to put together for an imperial stout. It will be my first imperial stout, so I just want some critiques. I'm guessing that I'll get around 65% efficiency.

4# - 2 row
1.5# - chocolate rye malt
.75# - chocolate malt
.75# - roasted barley
.5# - black barley
.5# - crystal 120
.5# - crystal 60

4# - Pilsen dme
1# - wheat dme
1# - corn sugar

70ish ibus of chinook or northern brewer at 60
1 oz - willamette at 10

Probably a few ounces of cocoa powder at flameout

Planned on making a big ol starter of either 1056, 1450, or pacman yeast. Not sure yet

Then I'd split it in to two different secondaries. Use some combination of either cocoa nibs, coffee, vanilla beans, bourbon and/or oak cubes.

How does the grain bill look? Is there too much roast? Use carafa instead? More finishing hops? Any other changes? Let me know what you think

3.5 lbs of assorted dark-roasted malts is a lot. But I believe that chocolate rye is softer-tasting than the rest, so you should probably be ok, as long as your mash pH is in the right range. You may need a few grams of baking soda to keep it from going too low. The 10-minute hops you can probably omit, their flavor will vanish by the time you drink this. What's the reason for the Wheat DME?

Thanks for the advice. I have a pound of wheat dme sitting around so I figured I just toss it in there. I might cut down on some of the roasted malts so it isn't too overpowering.

I have an imperial stout that's close to a lb of black patent per gallon, so an assorted 3.5lb for 5 gallons isn't crazy; it's just more than most people do. Rye is huskless, so chocolate rye won't have the over-the-top burnt flavors of roasted barley or black patent. I've heard it gives a milk chocolate flavor. If you don't count it, you'd only be at 2lbs of roast, so I say brew as written. It does look pretty tasty.

1lb/gal? that is aggressive, sir

Upon further review, it was 1/2lb per gallon, which is obviously a very different beast. It was pretty much the 1914 Courage Imperial Stout: http://barclayperkins.blogspot.com/2012/02/lets-brew-wednesday-1914-courage.html

Very tasty. Much smoother than an unaged, 9% abv, 10% black patent stout has any right to be. Everybody should make that beer.