Any drawback to keeping the drum spindles on my 66 Valiant?

I've got the original set-up (drums) on my 66 Valiant. I mean I went thru and replaced everything, brake lines included front to back, but its still just the stock set-up and it stops great! I live in Minneapolis and routinely travel 35W and it stops no problem from 70mph. In fact it stops better than my Dodge Ram.
Why the need to change? Unless you're racing it?