Too much engine work at once

Well, a 318, at 9.2, won't be that bad with that cam.The VP will be a little better than a low-C later 318.The math says about 7% better

But, for a 4speed manual; I'd get it on a 106LSA to punch up the pressure and the VP, and with headers, the overlap, at 47* will actually count for something, and best of all? you can get some fuel mileage out of it.
Yeah that's what I would do; an LSA of 106 and in at 105.
Here's food for thought
the Wallace says;.............................Scr./Dcr./psi./.VP
The original cam,a 240/112 looks like 9.2/8.15/164/136VP..in at 108
The new 256/112, in at 108 looks like 9.2/7.78/154/122VP
The...... 256/106,in at 105,looks like 9.2/7.93/158/128VP
But no matter how you slice it, 122 is soft.
with an Scr-bump ,the 256/112 looks like 9.7/8.19/165/130VP jus saying
howzabout a 268/104,in at102,looks like 9.7/8.19/165/130VP now yer talking. I would sacrifice 6 points of VP for the power of this cam.And to go from 9.2 to 9.7 is like 4.57cc...... so look; you're gonna loose compression anyway with the .039 gaskets over the factory steels,so you might as well shave the heads enough to compensate for both,(about .042) and stuff the 268* in there, then you only have to do it once;Cuz I'll tell you the 268/104 is gonna be a charger.... at 9.7Scr,lol.
Just remember, all that power is gonna be 800 to 1000 rpm higher than with stock cam, or 8 mph further up in first gear with 3.55s..... but at least your bottom end won't suck so bad.....122VP is pretty soft. Well I guess that depends on your idea of soft; a stock 8/1 360 2bbl makes about that.
Anyway
I'm just thinking what I wouldn't do. And 122VP is for sure on the list,especially when for a couple of bucks more, I could have 130VP and something like 25/30 or more hp,over the 256 the only downside being the lumpy idle, and a bit of lost fuel mileage over the stocker. But a possible gain at steady-state over the 256/112.
The 268/104 wants headers to make those 64* of overlap to work.The 256/112 with just 35* won't hardly care
Happy HotRodding