I recently sold a stock FXR frame that Id been keeping for a hot-rod build. Some time ago, I looked over the various after market frames and the Chopper Guys frame looked to be closest in design to the stock H-D frame. I would lean towards them.

On the other hand, do a search and you may happen upon a stock frame for sale. The first FXR frames held shovelhead motors but an Evo will fit. They also had the rear shock mounts pretty vertical while later versions slanted the shocks forward. Id say the original set-up would be the best for my purposes but some folks dont like the look.

Authentic FXR frames are kinda hard to find but they do turn up occasionally - with legitimate papers too !

 

Just checked and more than one genuine FXR frames are offered on ebay right now.