I have a Dynacom Scorpion that has such a cone...not for sale
You may want to reach out to Mad Cow and subsequently down the line to Rocketry Warehouse and to Curtis Turner / Performance Rocketry. I am almost positive they made a clamshell nose cone back in the day that worked with this tubing.
Yes, Dynacom in the day had such a cone and matching tubing I do believe. As mentioned above, I think Performance/Curtis made compatible tubing and nosecone at one time. Not sure if that is the case now.