Hi Scott, its not just your HC pistons that are to blame, its just as much to do with your cams and cam timing increasing cranking compression pressure!
Battery internal configuration gives XYZ parameters and one variable is CCA. This can be increased by manipulating the AH capacity and other design parameters etc to give higher or lower CCA.
You need one with a high CCA and figure less on size and AH capacity in total. I have been using Yuasa Powersports batteries in mine. These are a series they produced to give maximum CCA and for me in a tiny size battery too. I dont need AH capacity but you will need the best compromise as a high AH capacity may make things worse not better. A high AH capacity will necessarily have lower CCA. A high AH battery (eleventy zillion AH for example) may never reach full charge and may therefore not discharge full amps when required but that last comment is between you and I only, i am no expert as we know.
The 'powersports' variety are not spectacularly more expensive than standard Motobatt or lead acid generally but i have found them to be more short lived!! Nothing is for nothing.
I was getting mine from Halfords.
Cables; the highest current carrying capacity cable is not based on diameter or cross sectional area alone. The highest or best current carrying ability is with the cables with more but thinner internal strands. This gives greater 'saturation' of conductor per unit of cross sectional area. Vehicle wiring products do these multi thin strand cables in 'made up lengths' with connectors attached or you can do youre own of course.
Also; where the starter return is on the RHS rear of the engine cases with its six mm bolt, i have found it necessary to periodically clean this and mean it. The engine case gets a layer of aluminuim oxide at the point where the cable attaches and i scrape this off with a broad flat blade screwdriver back to clean alloy. If i dont, it wont start.
If there is any doubt about the earth return for starter motor continuity, you can run a temporary 'jumper' cable from that earth location to one of the long 6mm bolts that holds the starter onto the engine just to see if it makes a difference! Temporarily removing the starter chrome cover is a small price to pay to find that your cables are overheated, brown and crusty inside their outer sheathing where you cant see them.
AL