Almost all the information you're going to need for a swap is going to be located in the tech articles on this site, the sticky notes, or at rangerpowersports.com.
I supplied the shop i choose to replace my already-swapped 86 Ranger with the links on this site, and over at RPS, so they would have all the information they'd need to pull off a proper conversion (the previous owner did some really wonky crap) with a rebuilt 351w.
The major snag ended up being the headers, of course, which took a solid 2 weeks to work out.
You have few options there.
I went with the tri-ys, and they had to be pretty heavily dented in order to clear the steering shaft on the driver's side. An option there would be to go into the custom fab side of things and get a different style gear box for the power steering, and relocate the shaft with some smaller diameter u-joints. Maybe even adding some sort of bracket w/bearings in order to pull the shaft over to the frame a bit more to help out with clearances.
The other issue we ran into was the water pump and radiator.
Either delete the mechanical fan and put an electric on there, or put the electric on there anyways and include an electric water pump. Pricy, but you save a LOT of space doing it that way.
We're having some electrical issues, and the carburator is acting funky right now, but she's up and running.
But make sure you check the tech articles. Lots of useful information there. Nothing is going to give you a proper step-by-step guide, though.
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