Deciding on replacement intake (318, details in post)

I did the math.
On a 9.600 LA-deck, the 167s math to .0095 below deck. that is ~1.87cc
The pistons, as far as I can tell, have 5cc eyebrows.
the .028 gaskets are ~6.8cc
The 360 heads, by all accounts are usually ~72cc. I have none smaller.
Throw in 1cc for the crevice volume
That totals 86.7cc

at 3.91bore, the swept is 652.27
That makes an Scr of 8.52

The .028 gaskets need a rough deck, else the fire-rings like to migrate, and it doesn't take long.
With the .039 FelPros, the numbers work out to
(652.27 + 88.5)/88.5 = 8.37


Plugging that into the Wallace with a modest cam (Ica of 66*) at 500ft elevation (guessing OPs elevation); I get
Static compression ratio of 8.37:1.
Effective stroke is 2.52 inches.
Your dynamic compression ratio is 6.60:1 .
Your dynamic cranking pressure is 124.24 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of PSI is 6.50 :1.
V/P (Volume to Pressure Index) is 90


V/P of 90 is just about 3% stronger than a factory 225 slanty.
The Effective DCR of 6.5, is about 1.5 points low and;
and Cylinder pressure of 124psi, is a good 30 psi low for open-chamber heads, and the Q is so huge as to be ineffective.
If OP had a stock convertor and hiway gears, this would be guaranteed to be sluggish to around 3000 to 3500 rpm.
Thankfully he has a manual-trans and 3.91s..

Op said

My advice still stands. but now with a low cylinder pressure design), I would add; Notta chance would I run this engine, in it's current iteration, with any other cam but the factory-sized one. With an Ica of 48*, the numbers improve to
Static compression ratio of 8.37:1.
Effective stroke is 2.89 inches.
Your dynamic compression ratio is 7.43:1 .
Your dynamic cranking pressure is 145.79
PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of PSI is 7.33 :1.
V/P (Volume to Pressure Index) is 121

VP of 121 is similar to a stock 5.2 Magnum. I could live with that..... if I had to.

But If it was mine;
I'd still run a compression test to see how bad it is. Then if it sux as bad as I suspect, then
I'd Zero deck it rough, to hold those .028s, then install 60cc closed-chamber iron, small-port heads. With an Scr now of 9.85, a Q of .028, and modest cam with an Ica of say 60* , the picture changes to

Static compression ratio of 9.85:1.
Effective stroke is 2.66 inches.
Your dynamic compression ratio is 8.10:1 .
Your dynamic cranking pressure is 163.55
PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of PSI is 8.00 :1.
V/P (Volume to Pressure Index) is 125

Now you got an engine!

Couple this with the 4-gear and 3.91s, and you are guaranteed to have fun in any A-body, and especially so in a light-weight Valiant.
To save a lil cash, I'd try it with the current decks and .028s, for a Q of .038ish; but the heads gotta be closed-chamber. and the intake I would use, would have ports matched to the head, and a Thermoquad.
But,
I have this Dual-Port, I got from a member here a few years ago, that I've always wanted to use on something.
Ima thinking Magnum heads and a port-match, to go with that lopey cam. Or, I'd really like to try the stock 360 sized cam, with this intake;
Static compression ratio of 9.6:1.
Effective stroke is 2.78 inches.
Your dynamic compression ratio is 8.21:1 .
Your dynamic cranking pressure is 166.49
PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of PSI is 8.11 :1.
V/P (Volume to Pressure Index) is 133

Oh yeah, this is starting to look like fun.........


Since the current cam already has a lopey idle, I'd screw the Magnums on, or any aftermarket closed chamber LA-heads and redo the compression test. If it ain't too bad, then, with the OPs 4-speed, and 3.91s, I'd try it.
So, at this point, my only cost is the closed-chamber heads and gaskets, cuz I already have a spreadbore intake, and matching 4-bbl.
If the heads I get have small-ports, I have this small-plenum Excelerator looking for a home.................

Like @toolmanmike said;

I just narrowed it down some .....................
all that figuring is just mused ramblings till you know witch of the 6 sbm solid tappet cams isky makes that he's running, and its IVC point!! with isky solid tappet grinds with lifts from .425 to .580 and duration's from 216 to 312 there's no guessing where that IVC point is and isky ant sharing that info ether....id really like to know my self....i just hate guessing!