65 Barracuda 318 Rebuild, Cam, timing, lifters maybe a kit?

Those 315s are closed chamber heads, a good thing. And might be as small as 57cc. If your pistons are down in the hole as is typically .050, then you might be able to squeeze 9.0 Scr out of that engine just the way it sits. ........ which at your altitude,2600feet, is still gonna be a problem with just about any off-the-shelf, hydraulic lifter cam,bigger than the current cam, you choose.
The factory cam (240/248/112) with an Ica of 48* is predicted to make 149psi/126VP very good numbers for a streeter,especially at 2600ft elevation. By 55*Ica, the pressure is down to 141/114, which is about what an 8.0 smog 318 makes at sealevel,(135/113). If you are happy with that 135/113 number then you can go up to that 55* Ica with your 9.0Scr......... but before you do, you would have to verify that 9.0, cuz if my math is screwed up, you're not gonna get that 141psi and you might not like me very much,lol.
The reason I mention the 55*Ica, is cuz it can be had on a cam that is almost 2 full sizes bigger than stock , giving you about 300 to 400 more rpm at the top with it's attending extra horsepower, if you go there. If you never or rarely go there, then there is no point to a bigger cam,cuz all it does is steal low-rpm performance as can be seen by the loss of 8 psi cylinder pressure, and 12 points VP.
The best way to combat that pressure loss is to give up the 112LSA which does nothing for performance in a ONE-GEAR car. That 112 is strictly there to prevent falling off the cam with the very wide 1-2 split in the stock TorqueFlite transmission. This is why earlier I recommended a custom cam with the Lsa tightened up to 108 or even less.
If you had a factory 240/248 cam but ground on a 108Lsa,(instead of 112) and installed it at the factory 108 Centerline, then your pressure would stay exactly the same, but the 108 would move the power peak up about 100 rpm, but more importantly the overlap would grow to 28*, up from 20*. That extra bit would normally create a bit more horsepower, on it's own ,WITH your new headers. So this is a double whammy to HP; namely the extra rpm and the Tight LSA power bulge; tripple when you consider no loss of cylinder pressure.
So knowing this, and also knowing that the ICA could be as late as 55* and still be equal to a smogger 318 at sealevel, this gives you the cam option of at least 2 bigger sizes, perhaps a tad more, but it will require a custom cam.
Soooo, I tried a 252/260/108 in at 106 and got
9.0Scr/7.8Dcr/145psi@119VP, and 40* overlap now, which is just 4* shy of what the 340 stick had.
That should get you about 400 to 500 more rpm, so you are gonna need springs.
IMO, this is a pretty good trade; 3psi/6points of VP/ plus 20* overlap. I'd slide that hummer in there and never look back.
BTW
A stock LA360 also at 2600ft might make 120psi/112VP...... so you are gonna smooooke those at your elevation, at least to the top of first gear.

So figure out your exact Scr, and call your fast-ramp cam specialist; paying particular attention to Wyrmriders post #53, there is a ton of good info in there, specifically as to whom to call.