Everyday that passes, your plants are suffering without proper lights.

How many days left????

Yes, if you put them under HPS now, you would increase your main kola sizes and perhaps some secondaries but not much.

Veg state is where you 'prep' the plant for flowering spots....it is too late to do that now. It is too late to improve your plant a whole lot....but you can improve your main kola yields.

Its tuff to estimate but I would guess an HPS will quadruple your yeild over what you are showing now.

As for a hood....you can build your room around it. You dont need a hood.