Newer 2.3 DOHC head on 2.5
 

Does anyone know if this is a possible conversion? Was wondering if there's a head out there that could make my 2.5 DOHC

No, the Lima(2.5l SOHC) and Duratec (2.3l DOHC) engines are not related so no interchangeable parts.

Not sure if anyone has swapped motor and trans but that is what you would need to do, as well as computer and wiring, so probably easier to sell the '99 Ranger and get an '02 or later Ranger with the 2.3l duratec engine .

There are turbocharger options for Lima engines, these were stock in some cars so parts and computers are available for the conversion or swap.