Me, myself and I would opt for the stroker motor.... or possibly a turbo kit on a low mileage H.O. engine.... but then I'd first rebuild the H.O. motor regardless...but that's just me :-) Unless your current prime mover is at death's doorstep, I wouldn't waste my time swapping the LoPo six for the HiPo job...that cost/job will be required in either event so you have to consider what the fruits of your labors will be. IMHO, there's really not much difference between the two versions of the 4.0L to warrent the hassle of yanking your real old motor and slipping in a newer old motor. If you're going to buy an H.O. engine and rebuild it, then that's a cost you could put towards the stroker motor.... which has already been rebuilt and improved. Save your pennies for the engine that's going to make you smile the biggest when it's all said and done.
mike