Does anyone know if and where I can find a performance upgraded intake for a pushrod 4.0 l v6.

I have recently rebuilt my 4.0 l v6 pushrod engine and I'm hoping that I can get the absolute most power out of it. Ive had it bored .020 over, with aftermarket heads, Competition cams, valves, springs, you know the "Works." Been having a lot of trouble finding aftermarket performance Intake and exhaust headers. I've been told that nobody makes said parts and it's all I can do for the most part. Any suggestions would be greatly appreciated