Guys running lil red's do good with them, cast 77 for 78 and so on...but you do with what you have.
I do think the 77-80 something ports are slightly diff between the 70-74 heads, let alone in 74/75 the addition of air injection bosses on the exhaust floors.
People say to try and use them as more st, but they are a lil too far off from the seat to really utilize.