That stiller looks like a winner to me, but I don't already own a 40X. From a purely cost perspective it's probably the best option if you don't already own one. a 40X for a donor rifle isn't exactly cheap and with the stiller the conversion work is already done and you just need to build the rifle out from there. That said if you've got a 40X already, then I'd be looking hard at the conversion Drawings/mags from Ravage 88 and having Chad @ LRI do the work since he's been around the rimfire block more than most.