Converting from sealed beam to Halogen headlights

[ChristiaanV]

Planning on doing this conversion, I wonder if I'll be able to get the slightly curved lenses instead of flat ones to fit?
So I should be able to use the existing loom to power/activate the relays, while running new thicker wires through the relay switch? I can draw negative from the body, and is it better to draw Positive from the battery or alternator, or just join it to where the rest of the loom draws it's power from?