When i went hunting for my crossflow it didnt take long to find one- £120 but i stripped it anyway and whacked some new main bearings in it. just keep looking - check out everywhere- not just egay
Gearbox was £25 - easy enough to find.
If you stick with just the standard 4sp escort box as I did then it does slot in very easy. and the gear box support on the viva lines up exactly with the escort mount but you need to make a simple spacer.
Plus I ended up having to grind a 3 " slot out of the fire wall lip - as I mounted the engine as far back as possible and then tried to fit my posh alloy rocker cover...
Mines only probably about 90-95 bhp- its a 1660 with a escort sport cam.
They are so easy to get all parts for including electronic dizzys and all sorts of upgrade bits.
Main thing for me was it looks the part and was an easy cheap swap, plus its not going to strain the axle.
It sounds lovely too- especially when i floor it and the secondry on the weber carb opens