The Candlepower is the only 350/400 H4 headlight I have been able to find in the last 10 - 20 years. I actually use a Cibie that's been NLA for a long time: I prefer the Candlepower light pattern after comparison, but the Cibie one is glued into my headlight ring and I'm too lazy/cheap to change it.
You will have to fiddle quite a bit to mount the headlight, it does not have the Stanley fittings that the stock ring expects. I believe my solution of gluing the assembly to the ring is effective and somewhat easy. Silicon sealant/adhesive has held it in place for many years without trouble - plus there's no gap for crap and bugs to get blasted inside the bucket through. There's no horizontal beam aiming adjustment possible, but I consider that unnecessary anyhow.