Best next upgrade?

I guess the notion of a 'weak' 7-1/4 has been a little vague for me. I get that a built 410 stroker with slicks will eat it for lunch, but will a moderately built 318 with radials ever take it out? It's not clear and this is my first Mopar, so i ask the advice of the board :)
I'm on the prowl for 8-1/4 or 8-3/4 locally now, but it looks like it will take some patience to find a good deal...
I think I have a video somewhere where my wife goes... "Ut oh!"... When she was filming my duster at Woodburn and the 8 and 3/4 snapped on about its 20th pass..
Don't worry about breaks there's a cornfield at the end of the drag strip that'll catch ya .. LOL...