It depends on which 2.3 you get from a Ranger.
The one used until the mid 90s will fit with few issues (there were a few things that you'll need to re-use from your older engine).
The one used from the late 90s up will not (it's an all-new design)
The 2.5 is different too I think, but I'm not 100% sure on that.
When it comes to forged 2.3 pistons, Racer Walsh carries them, as well as a few others, there's a 2.3 parts thread going already with a list of places to get parts.
If you really want some more displacement, you can have your 2.3 bored out and/or get a stroker kit for it.
__________________ 1976 Ford Mustang II Ghia: 302 with a 600cfm Edelbrock carb, Edelbrock Performer 289 intake, Dynomax Blackjack headers, 2.5" exhaust with Flowmaster Super 44s. RJS 11-gallon fuel cell, C4 tranny, chrome 16" pony wheels, fuzzy dice, brown vinyl half-top, and painted in the tackiest color ever (harvest gold, that's why I call it "The Goldenrod").
Also have a 2003 Dodge Ram (lightly modded daily driver/tow rig/office/dining room/home away from home/workshop... I call it "The Big Blue Dawg".) | 
Ranger 4 cyl in mustang 
