Intake Manifolds

yes
But like has been said, which one?

But honestly aftermarket intakes favor high-rpm power. So if your cam is stock or 340 sized, you'll be hard pressed to improve on the stock cast-iron dual-plane units.

If you want bottom-end torque/power, from a particular engine the thing to do is get the cylinder pressure up . The
135psi of the stock 318, is abysmal.
145psi is just less abysmal
155 is starting to come out of abysmal
165 is about the upper limit for iron open chamber heads.
As to closed-chamber/tight-Q, alloy heads
175 is about the minimum
185 is nice
195 is approaching the upper limit; and yes, I have run this, still on 87E10
205 is about the limit with best pump-gas. Very few on FABO admit to running here, and AFAIK, it was always with strokers.
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I can tell you that 195 is waaaaaaaaaay more than you need with a 360, on the street.
I am currently running 180, which IMO is a only just barely, a lil more than adequate lol. I wouldn't willingly run much less.

If I had a smaller engine,
with less stroke, I would be searching for more pressure. Almost invariably, with a 318, this means an earlier-closing intake event. For performance, I would NOT run open chambers unless with tight-Q specialty pistons.
For bottom end, I'd consider a long, small diameter intake runner, tuned for that. Second best would be a dualplane.
On my 318car, I installed a factory cast-iron smallport 4bbl with a big TQ, and it runs gangbusters, at 140 psi. But that engine was only used for my winter engine. My son was so impressed with it, he made me an offer I could'nt refuse. A few years later, he got a girlfriend, and traded me his beater D100 with my winter-engine in it, for a fresh old Grand-Am that I was driving. Oh the joys of having children. They each, all three of them, inherited one of my beaters, and a small sum to help with making a down-payment on a house.
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135psi is for lawn mowers.
Even my dead granny wouldn't run 135psi.
I would have said Grannies, plural, but my Father's Mother, born in 1905, long dead now, had 15 babies, the last of whom, now also dead, was just 10 year older than me, and Grandma never did learn how to drive a car; so you know, I can't speak for her, lol........................... but man could she bake! When I get to the otherside, Ima gonna go look for her, and invite her to come and cook for me, cuz I can't even make Kraft-Dinner right..
My grandma was nearly 60 years old when her baby finally flew the coop, and only because her husband, my Granpappy died, and Her family relocated Grandma off the farm, to a small retirement home, in a nearby city, where she could walk to visit friends. Cuz you know, she was only 60 and couldn't drive.
My guess is, that if she couldda driven, a sucked-out 135psi 318, wouldda been the hot-ticket for her, cz in 1965, everybody was still driving 6-bangers and flat-heads, lol. It's all about perspective, I guess.
Well except for Uncle Garry who had a monster tail-dragging Oldsmobile with a pair of sky-scraper-tall CB antennas mounted on that tail-dragging rear bumper, lol. To be fair, this I saw on Uncles Wedding-Day, thru my 12 year old eyes. Hyup, he's dead too. The boys are all dead. Of the 15, just the baby-girl is still breathing, but that won't be for long. She was never the healthy one, but she outlived them all, hah! She'd be deep into her eighties today, maybe into the nineties, which would then also make her the longest-living of the team.
But I digress, lol.