Mounting Thermoquad to air gap style intake. What adapter?

Plugging your numbers into the Wallace Calculator, it predicts your CCP to be 155psi and your Dcr to be 7.79
My thoughts;
That modest pressure means your engine might be a tad soft at sub-3000/3500 rpm,
which means together with the modest camshaft, she really wants the bottom-end to be picked up; unless you have a higher than 3000 stall Convertor.
The small-valves and modest cam are gonna limit useful top-end.
The 108LSA predicts ~58* of overlap, so that will want headers to plump up the midrange, and it squeezes a bit more power over the nose. That usually steals bottom end, but in your case @218/224/108, this will not be an issue.
The AG intake is a very good intake, working thru-out the rev range, and to beyond 5500, where, normally, a Single-Plain would be called for. But in your case, that small cam is peaking at about 4800, and the 108Lsa is gonna run down the backside of the power curve pretty quick. So it's not likely that your engine is ever gonna take advantage of the best feature of that AG intake. And so, IMO, that AG-style intake, squeezed under the factory hood, is overkill for your engine anyway, and so swapping it out opens up other options.
Options like; with the carb lowered, you can run a filter box with an air-straightener under/inside it, and a cold-air intake, both of which should plump up the entire rev-range with a lil bump at the top to compliment the 108LSA.
Taking all those factors into account, and the need for hood-clearance; my Suggestion would be to swap that AG-style off, in favor of a low-rise, midrange intake, that is set up for your head-ports, and then install that bad-boy Thermoquad.
The big 850TQ is overkill for your combo, but, properly adjusted, will NOT be a problem. I run those on 318s all the time. With the factory-stock cam even. The TQ will allow your small-cam/modest pressure 360LA to continue to pull a lil further up the rev range before "falling off the cam"
I just don't see your engine taking advantage of the AG's top-end capability, so swapping it out, for me, is a non-issue. It won't hurt your combo in any way, but I doubt if you will miss it after it's gone...... unless you install a real dog of an intake, I guess........
So that just leaves the decision as to which intake to run; and several good recommendations have already been offered; just make sure it comes with the right spread-bore mounting pad.
If you have a factory iron spreadbore intake, I would give that a try; they are a pretty decent piece, and come with a choke-well, and maybe all the mounting points for the A/C stuff.
This 360LA short-block with the 218/224/108 cam, will make plenty of vacuum no matter what street-intake you install.

BTW-1
as previously mentioned, I heard/read, that Carter carbs are rated differently than Holleys, so the 850TQ, a Carter, cannot be directly compared to a Holley. Maybe that's part of why they can be installed on just about any engine; IDK.
But one thing I do know, is that the TQ has ~11.5 square inches of throttle-valve, versus ~9.6 in the 750DP........ whatever that means, lol.
If you have an automatic, the DP is not that desirable a feature.

BTW-2
A streeter is usually a two-gear car, running to well past 65mph in Second gear. Meaning it only goes thru the power peak ONCE to get there and usually, with a 360, the tires are spinning thru first gear anyway. So then I see NO point in top-end power.
If you are running an automatic trans and say 3.23s, then in Second gear, with 27" tires, 65mph @WOT = 3800@zero-slip, say 4200 on the tach. So what's more important to you; power at 4800(75 mph), or power at 4200(65mph)?
But if you are running 4.10s, Second gear at 65 mph comes to ~5300, which is an excellent rpm for your engine combo. ..... And the AG is still not working hard .......

BTW-3
If you have a 3000 or higher stall, then the bottom-end is less important, almost not important at all.

These are my thoughts;

Happy HotRodding