The x400 chainrings won't be ramped and pinned and could very well be biopace. That being said, I've put newer ramped and pinned large rings (all you need on a double, no need for ramps nor pins on the smaller ring) on older cranksets in the past with amazingly positive results in front shifting.

I'm currently running a 6600 large ring and a superbe pro 38t ring on my 9 speed (6510) race bike. Shifts great.