Change efi or change intakes????

Well that looks like a dynomite street pkg.

And again let me say I have no knowledge about 416s.
I can say that in my 367 that cam would definitely want a single plain. If I imagine that your cam is advertised about 284* and is a 110LDA in at 108, then your 10.7 Scr translates to 8.23 DCr, with about 166 psi cranking cylinder pressure. This is a great street place to be, and with aluminum heads should be comfortable on 87 gas. With a 367, 8.23 might be a tad soft off the line; and would want some rear gear. But I can't see that with a 416, and especially not yours, and its 9.58 starter gear and 3000TC. So you could probably give up a lot of torque under 3000 and would never miss it. Conversely, as a streeter, you don't need any more up top. However, your starter gear dictates a 7500rpm shift into second at 60 mph, with 27s out back and 5% TCslip. That wants a power peak around 6800 and the ported heads to stretch it out.But your cam will likely peak a thousand rpm sooner; soooo that's not gonna be the fast way to 60 cuz you are gonna have to shift. And I'm gonna guess around 6400.
That 6400 will get you into second at about 52mph.At that mph second comes in at 3850ish, and now that 416 is gonna show it's worth, cuz my 367 is a little soft down there, with a lot less cam, and more Dcr.
So what all this boils down to is this; If I am remotely close on the 5800rpm power peak and a 6400 rpm shift speed, then you don't need a big singleplain. In fact I would stay away from it, cuz pulling from 3850 with a big single,IDK; it's a good thing you have a 416.
But your 416 should be happy with a medium sized SP, not an Excellerator,lol.
Now, as to which one I can't say, there's lots of waaay smarter guys than me on FABO, that will be along shortly. But I would sure try to make that RPM work, cuz it's about the right one for a streeter. The AG would be a bit better for sure, but it's pretty tall too. Here's an idea; how 'bout drilling every runner up near the head-flange, and injecting the Nitrous there? Might that be the best solution? IDK. If nothing else the plumbing would sure look cool.