Thanks, it is as I thought. Like I said, my plan is to move to LiPO4 in two stages: first to set up a more futureproof wiring/charging and starter battery, and then - then the lead/acid batteries die - move to Lithium.
The main reason why is that is quite expensive to move direct to Lithium. The batteries are expensive, but it is the electronics, specifically the new voltage regulator and charger, that really bump up the price...so doing it in one go is rather expensive!