Best way to proceed with improving up 427 Windsor street setup

[Anthony]

A good dual plane will still make good power.

My "stock" 427 FE, (429 ci) with an original 1964 dual plane intake, original style heads, 1965 holley carburetor 3255-1, made about 30-50 more hp and torque than the roush 427R crate motor, with "state of the art" single plane intake, heads, and carb , tested on the same dyno.

[blykins]

I would lean towards that 427R being hurt then.

I've built/dyno'd a few 427FE's with factory parts and they wouldn't touch what a Roush 427R should make by a long shot. A Roush 427R should be in the 525-550 hp range. You're saying that your FE with all factory parts made almost 600 hp?

Not saying you're wrong on what you saw, but logically, that should not be correct.