Thanks Fred.
My plan is to use LiPo batteries, but I also plan to add the difference between their weight and weight of the 6-volt sla battery that they will replace, in the form of shot, below the plywood deck that is glued to the bottom of the hull. This should actually lower the cg of the model.
My plan is also to replace the lead plates, that were simply sitting on the plywood deck, with shot that will be located between the deck and the hull as well. The eight-ounce speaker magnet will - I think - sit on the top of the deck where the lead plates are currently. I am, however, contemplating a hole in the deck that the magnet may sit in, lowering it even further.
I was a little alarmed by the lack of security of the lead plates. Seems to me that any fairly violent roll could actually dislodge the plates, greatly changing the trim, and almost certainly sending the boat to the bottom. Perhaps it was only intended to sail on very calm water.
Gudmund