I know it's not what you asked - but have you considered a Suzuki J20A (2.0 99+ Vitara/Tracker)?
127hp |removethispart|@ 6000 rpm
134 ft-lbs |removethispart|@ 3000 rpm
I have no idea what the weight is, but it's all aluminum, and if I'm not mistaken, the 22R is a cast iron block, so the J20 should be lighter, and they've been swapped into the Samurais before, I believe there's even a kit available from Trail Tough.