Chocolate Oatmeal Imperial Stout Recipe help

I'm trying to formulate my first recipe. My ultimate goal is to create a semi bitter chocolate oatmeal imperial stout. I've done some googling for recipes and have gotten a general idea for what has worked for others, and want some insight on my take of it. I'm kinda lost as far as how much of each grain type I want. It seems like most recipes I saw were fairly balanced. I'm very open towards any suggestions! : )

I would consider Hoppin' Frog Boris the Crusher a good example of what direction I'd like to go in.

Recipe type - Malt extract
Batch size - 5 gal
Yeast - Wyeast 1056
Est OG - 1.096
Est FG - 1.024
Est IBU - 47
Boil time - 60 min
Est Color - 53 SRM
Est ABV - 9.6%

Ingredients

Fermentables
10 lb Briess Light Syrup
1 lb Chocolate Malt
1 lb Malted Oats
1 lb Crystal Malt 120L
1 lb Roasted Barley

Hops (boil time)
2oz Willamette 5.3%AA (60 min)
2oz Fuggles 4.0%AA (60 min)
1oz Willamette 5.3%AA (10 min)
1oz Willamette 5.3%AA (5 min)

Misc Items (boil time)
8oz Cocoa Powder (0 min)
1 tbsp Vanilla Extract (0 min)

I'll probably leave this in the primary for 2-3 weeks then go straight to bottling. I figure 3/4 a cup of priming sugar will be fine.

A few things:

Oats (malted or flaked) need to be mashed, not just steeped. Malted oats do contain the enzymes needed to convert starches to sugars, but you have to hold them with the right amount of water (1-2 qrts/lb) at the right temperature (~150) for the right amount of time (45+ minutes) to make it work.

Otherwise it looks like a solid recipe to me.

I would aim lower for carbonation, a big rich stout doesn't need as much carbonation as many other styles, low carbonation will make it seem creamier. I'd suggest using a priming calculator that takes the temperature and actual volume of beer into account.

Vanilla extract is very delicate, I'd add it to taste at bottling (or toss a split vanilla bean into the wort after fermentation ends).

I would give it a few weeks in secondary to clarify and make sure fermentation is complete.