The only real reason for a 90 min boil is if you are using a lot of pilsner base malt in your mash as the pilsner malt has more of the DMS precursors and creates more DMS to boil off.
You don't have any times in your hop schedule so I can't really comment.
according to Beer Calculus (free online beer recipe calculator)
you are looking at 1.106 OG for that malt bill (note I subbed 7.5 lbs Dark LME for "7.5 lbs Coopers Stout LME")
Because you are using a pre formulated stout LME it is hard to say what grains/hops they used in making that extract since I haven't used it myself. So I have no real guess how it is going to turn out.