Reverse Split Pattern Cam - 318 Magnum Head swap

Well if it is backwards ,
I sure wouldn't put it in at 106*.. unless your Scr is really really low.
In at 106 it sets you up for an ICA of 56* which is great to make compression with, in a Low-C engine. But that stinking 112LSA then makes the power stroke just 106* which ain't the best for fuel economy. But if your Volare has 2.45 gears well then she'll need all the cylinder-pressure you can find. For this reason; I'm no fan of wide-LSA cams.
However if the Volare has something like 3.23s, now, for mpgs,she'll want some help in power extraction. So then IMO an install of 110 to even 114; would make some potential for mpgs. However, the cylinder pressure would fall significantly at 114*.,requiring an increase of about 10% in Scr to overcome, which works out to about 10cc less total chamber volume. Since the top end is coming off anyway, just shave the heads and presto!
Because this is a 112 LSA cam, and say you put it in at 110 and 8.8Scr with any sub 3.55 gear; the power delivery is gonna be somewhat like an electric motor. It won't feel very powerful, but watch the speedOmeter, they don't lie.
I hope you also kept the automatic from the Fifth, she's a 2.74/1.54/1.00 unit, most likely with a loc-up feature. That's a great trans for this combo.

But if it's not backwards, I'd install it at ~108 for an Ica of 60* and extraction of 110*, good to go with shaved heads.

Here's my theory; if the extraction is less than 100* she will be a gas hog. Between 100 and 108, she just gets poor fuel mileage. From 108 to 116 it's getting somewhere. By 120 or better yur passing filling stations and smiling.
The above is only true when the cruise rpm is kept reasonably low, yet high enough to keep the engine out of reversion.
And the cylinder pressure is close to as high as possible for the fuel you are using.
In other words;
A)you can't expect fuel mileage with big cam, like a 276/284/112 cam at 8/1 Scr with ANY gear, especially one that keeps the engine in reversion. Partly because it has no decent pressure, partly because some of what little it has is going back into the intake, and mostly because at cruising-rpm,power extraction is just too short, and a lot of energy is going straight out the tailpipes.
B) the stock 318 does pretty good with the 240/248/112 cam in at 8/1 with nearly any gear. Partly because nearly all the pressure it makes, goes into compression, partly because at hiway-rpm it has no measurable reversion, and partly because it has a very long extraction period.
If these guidelines are used, then the lower the rpm, the higher the fuel economy will be.
So, if you want BIG mpgs all you gotta do is select a small cam with lots of power extraction,in an engine that makes a lotta cylinder pressure, and gear the car to idle down the hiway. and after that 3000 pounds is waaaaaaay better than 4000; at the high end,every pound counts.
Well there comes a point ,lol where power extraction could I suppose become too great for what little fuel it is drawing in, but Ima thinking the factory 318 cam (240/248/112) is about as small as anybody would ever install, and it, in at 112, about as retarded as one might consider;still has a ratio of 128 compression to 120 extraction (48.387% exhaust); whereas your 264/260/112 in at 106, has a ratio of 122 compression to 108 extraction (46.96% extraction).
So no worries.