X heads that flow 250 on 416

moper said
They'll work fine and I'd estimate around 430hp and 490ish torque. I don't think you'd be disappointed and you can always upgrade later.

I totally agree with Moper!!!

I also have X heads on my stroker with a thumper cam and am getting 320hp to the ground. I too would like better heads and a bigger cam, but it runs nice, I would put it together and run it you will be happy, and can upgrade later. JMO