392 in a 70 Duster

What about using an aftermarket intake manifold like the Prefix/Arrow single-plane?

I picked up a complete 2014 5.7 out of a truck with a bad cam lobe and lifter and only 137k miles for $600... for the cost of stepping up to a 6.4 I could buy conversion headers, aftermarket intake manifold and possibly a QA1 k-member. I plan to use a factory replacement 6.4 SRT manual-trans camshaft, with all that should be 450-500 HP. Then again if I found a ready-to-run 6.4 I wouldn't need to buy a new cam and lifters... oh well this probably isn't happening for another 3 years anyway lol.