I don't much care for the look of that DIPA recipe. it might be fine but I would skip the amber LME and double the DME then add some color with specialty steeping grains. keep the sugar though.
the 90 day secondary ageing on oak seems exteme but as long as you wait to dry hop till after it might be fine.
I think the stout, barley wine, or wheat wine is a better way to go. the alcohol in the grand marnier won't hurt the yeast because it'll be maybe a cup in 5 gallons. it won't increase the ABV significantly. I would soak some oak chips in the GM and age to taste.