i think i remember something about the front neck rake being less than pan frames and this added to some satblity problems, also about the springers doing a little hopping when into sharp cornering. just a thought!
Do you have your spring thru bolts bridged? I was looking through Uncle Franks manual last night and there is a comment in there about the old HD's and excelsiors having stability problems and adding a bridge across the bolts??? Beats the hell out of me!