Cam caps are technically not replaceable. Thats why Honda doesn't sell them separately. They are machined with the head so a different cam cap may not work and may cause cam damage.
I would just reuse that damaged cam cap and run the distributor with only the 2 lower bolts. *Dont over torque them, just to spec is fine. OR find someone to weld some material onto that top piece then drill and retap it.