Cylinder Head Choice

Stick with 318WILLRUN.
To answer you’d question above about where to get ported heads....
Shocker 185 Mopar CNC (Sold in Pairs) - PROMAXX Performance Products
I have a set of these and there good. Not to much head for a 318.

These are perfect and right in my budget, especially considering the aforementioned Black Friday sale.

I’m slightly confused about the gear ratios and the torque converter. Would I need to buy a new rear end before getting the converter? Is that the only way to change gear ratio to 4.11?

This converter seems to fit all of the specifications you suggested as well - would this be a good one? thank you for all the help!

TCI 751400: 10" Streetfighter Torque Converter 1972-80 AMC Torque Command 727 | JEGS