Hop amount and schedule for SMaSH IPA

I am planning a British style SMaSH IPA made with Maris Otter and East Kent Golding (6% AA).

I am doing a 15 liter batch with a estimated OG of 1.056. I a not sure about the amount of hops and the hop schedule, though. What do you think of 20 grams @ 60, 30, 15 and 5 minutes (60 min boil)?

This will be my first batch, so I don't really know what flavour profile I want, but I am generally not a fan of super hoppy beer.

This will be more of a pale ale than an IPA. I've used almost that identical hop schedule before for this exact smash. This will yield a pretty solid english style bitter, depending on your yeast choice. If you're trying to get a feel for EKG and MO this combo is solid. Slightly bready, earthy and very drinkable. I'd leave as is and brew away!

And to make it an IPA you would increase OG and/or hop levels?

Just a quick adjustment... Double the 60min addition and move the 30->10, 15->5, 5->0 (flameout). That will give you the most out of your hops as far as flavor and aroma go with a fair amount of bitterness to balance everything out.
If you dropped 15gm from the 60m addition you'd have a nice English bitter.
Leave them as stated for a true English IPA.
And I recommend using a British yeast. S-04 is my favorite.