Comp cams xe268h for 318

On a sidenote, if the ring-grooves spec out ok, and the pistons are reuseable, then you can get those nice bores machine-honed straight, taking out say;a thou to a thou and a half. Yes the skirt clearance will be a lil loose, perhaps noticeable when cold. But you can minimize that with running a lil hotter coolant. And IMO, straight round non-tapered bores are more important than a lil noise on start-up.
With the bores now fixed, I would run file-fit Plasma-Moly second ring kits. You may Leakdown the engine afterwards and find almost zero leakage. And that spells performance. I have done this several times; the caveat being pistons with decent ring grooves.
Ring gaps vary by a factor of 3.1416 for each .001 of bore taper. So if the bottom is 3.910 and the top is 3.911, The gap will grow from say .035 to .038 and change . And when it gets to the top, your 135psi may be just 130; a 4% pressure loss. That is bad. In the meantime, the expansion and contraction of the ring is constantly wearing the piston groove, and the pressure loss into the crankcase is overpowering the PCV system, and polluting the engine oil with fuel and carbon.
You need to combat the skirt clearance to keep the piston running straight up and down in the bores to keep the rings in full contact with the walls. To do that, I increased my minimum running temperature, little by little until I hit 205*F . With almost immeasureable Leakdown, I stopped testing. That was 2004. That engine has accumulated more than 60,000 mile since. Yeah, on cold summer mornings, the pistons do rattle for a minute or two.
Oh yeah, with the new higher minimum running temp your cooling system has to be up to the task of keeping it there.