Not sure if you can get any Langdon headers anymore since he is now retired. Tom over on 12bolt.com may have bought his remaining stock. Careful with Clifford as some people have had trouble with them filling orders in the past. You will send them your money and not but they will never notify you if they actully have the intake in stock or not. I would call them first before you hit the Buy Now button!
I would check out Aussie Speed for a 292 intake they have alot of well made stuff. In fact I am in the process of doing a 225 slant six with there products.
Here's some eye candy to keep you motivated!
