For starters, even the original 6.0 had a bowfoil. The jib sheeted to the track on the crossbeam. The N/A had the overlapping jib and more roach in the main which required a stouter mast with double diamonds. You may have been rated an N/A because of the squaretop. Regardless, a N/A with a chute is still rated slower than a N20. Looking at the picture, did you have a roller furling hooter on there along with the endpole snuffer?
As far as altering the rig like Roy says, keep this in mind; The last Milt Ingram Race I did, Roy and another guy showed up with two 6.0 N/A's rigged that way. They made it well known that they were going to destroy all the N20's with those rigs. They looked nice at the starting line but I never saw them after that. It was a light air race and they were so far back when we rounded the first rig, we couldn't see them anymore.
If you go that route, lengthen your bridal wires three inches and shorten your shrouds about an inch and a half or less.
One of Roy's buddies showed up with one of those rigs one year and I beat him boat for boat with my old Hobie 21 (600+ lb boat). The 6.0 is a smooth ride but with all the money you'd be putting into it, you could get an N20 and be done with it.