[banjo-guy]

 I want to use up some ingredients for a hoppy, but not super bitter IPA. I have a lot of Cascade and Amarillo in stock. How does this look?

2.5 gallon batch
4.1 gal. Distilled Water
4 oz Munich  4.5%
4 oz Vienna  4.5 %
5 lbs Pilsner LME (Briess) 90.9 %

.25 oz Cascade 60 min

.75 oz Cascade 15 min
.50 oz Amarillo 15 min

.75 oz Cascade 10 min
.50 oz Amarillo 10 min

.75 oz Cascade  5 min
.50 oz Amarillo  5 min

.75 oz Cascade Whirlpool
.50 oz Amarillo Whirlpool

One package US-05

1.5 oz  Cascade  dry hop
1   oz  Amarillo  dry hop

I could partial mash or steep the Vienna and Munich. If I partial mash should I reduce the LME to get the abv down to the 7.0 that I would have by steeping? How do my % of Vienna and Munich look?

Brewing an extract batch with steeping Vienna and Munich Beersmith calculates:
OG 1.069, IBU 72.2, Estimated ABV 7.00, Bitterness ratio 1.043

Partial Mash gets:
OG 1.080, IBU 70.5, Estimated ABV  8.1, Bitterness ratio .879

I've never done any water adjustments but I thought I might add gypsum to enhance the bitterness. How much and when would I add it? (is a good idea to add it?)

Thanks for any help and suggestions. I will be brewing this during the hugh blizzard that is heading to the East Coast.

[erockrph]

I'd definitely partial mash the Vienna and/or Munich - they need to convert their starches, so steeping alone isn't always sufficient. You will probably be OK where you're at with the quantities, but I'd be tempted to just pick one and keep it at the 5-7% range if it were me.

Hop quantities look good. I've moved to doing all my late additions in the whirlpool, but the 15-10-5-0 "hopburst" schedule has produced some fine IPA's for me in the past as well.

I would try to get the ABV down to 7% or under if you're shooting for an IPA vs a DIPA.

[banjo-guy]

Thanks for the suggestions. I'm going to eliminate the Vienna. I'm using the grain bill from Brewing Classic Styles. It has a very small amount of C10 and C40 in addition to Munich. I've used his grain bill before and loved it. 
I've also put the hops at 10,5, and 0 minutes, eliminating the 15 minute addition. I've added  Simcoe to all of the hop additions.
I like my IPAs around 6 or 6.5. ABV. And brought the ABV down.
I BIAB and really haven't partial mashed or steeped in a long while. I'm not used to doing it.
Do I have to treat distilled water if used for the mash? I might mix some filtered tap with distilled for the partial mash so that the water has some minerals ect...

I'm brewing this in the morning. Any suggestions after that will be too late.
Thanks again.