I'll throw in on this build, as it is pretty close to the approach I took with my 445 truck, minus the juice (although the truck has swallowed plenty in my early years)
I'll speak to the gorilla in the room first, 200 hp of nitrous is a lot, I am not sure I'd feed it that much, but if you do, you likely need a dedicated fuel supply, an ability to retard the timing, and keep in mind, you are seriously pushing the limits of a 390 block, it may split or crack. I have run bottles and bottles of nitrous through stock block 351s and 390s in younger days at the 100-150 hp range, but that much is pretty serious unless you 2 stage it, keep timing early and fuel plentiful, and even with that, I am not confident those cylinders or the mains will hold their shape if you really put that much juice on top of a 500+ hp build. Just sayin, and I used to love the stuff....
For the rest of the build, the plan looks good for a street 445 and should be faster than that bird should go, I'd say in the low-mid 230's for intake duration, more on the exhaust, especially if there will be spray. On FEs, we have found a little lazier ramp does good, even when magazines say they dont
I think a hyd roller with 290 intake/300+ degrees exhaust duration is reasonable and will tolerate a little more compression, you'd have to look at intake centers, but my guess is you can go pretty early if you stay around 10-10.25:1. It'll be real strong, REAL strong and a common 110 LSA would have about 75 degrees of overlap should have some nice chop. If you want to spend more money, spend it on the heads, that's where the power is.....
FYI It's not far from my combo in the truck but I have a little more head, but maybe less intake with a ported RPM and a 1000 Holley.
What I really do NOT like is the combination of the low first gear and the loose converter, I'd stay under 2800 with a reputable converter company that builds it for YOUR combo, because it's heavy and torquey which will drive a bargain converter higher and this build doesn't need it PLUS your wide ratio tranny is likely too deep, 3.5 X 3.8 = 13.3, too much, especially with the multiplication of the converter. I would run a stock gear set unless you are running 30 inch tall tires.
Good luck, certainly sounds like a crazy bird!