Can someone shoot me straight on an idler arm question?

I should be good here man, I'm putting in a mild 340 and 727, 11.75 brakes and a 8.25 with a 3.21 I believe sure grip. It's a 67 barracuda convertible and it'll be used for back road cruising and an occasional beach run. I anticipate rarely putting my foot to the floor. The 340 has X heads and a 474 lift purple shaft cam. I love that sound. It had a torker II with a 750 dual feed double pumper, but that was pre marriage and in a 68 hardtop valiant with headers, a decent converter and 3.55's. So the torker will be coming off for a dual plane either thermoquad or holley 600 with electric choke. I can't scare my wife too bad or she will never ride in it. I'm also concerned about how much twisting the convertible can take, so I'll be driving as gingerly as my stones will allow me to.
Put decent subframe connectors in it, and never worry about that.