You have 2900 lbs of ballast in a boat that dispalces 5800 lbs. that is a 50% ballast ratio. that is huge. You don't need any more lead.
The folkboat originated as full keel wooden boat, a very traditional design. This type of boat always shows poor initial stabilty due to their narrow water line and veed hull shape. It is very normal for them to rock a bit as you step on the side deck. Also since thay depend largely on the keel weight for stabilty they commonly heel to 20-30 degrees, that is normal.
Think of how much heel you need to have before the righting force of the keel comes into play. They do get very stiff beyond this, you will just have to get used to it.
A more modern vessel, has a flatter bottom which increases the intial stabilty so typically they have a lower ballast ratio, 40% might be more common now.
We have some very beautifull wooden folkboats in our club, I was admiring a couple today.