Nah, all you need is a turbo. Bebuild the engine with forged pistons, throw a T3/T4 on there, crank up the boost, have it dyno tuned and you'll be putting 300 to ground. 5.0L ranger's won't even be able to keep up.
I know, I know, "that's so much work, money, and down time!". Just go to youtube and search for "turbo ranger" and watch a few videos. You'll quickly decide you can't live without a turbo.
FWIW, my swap ended up costing me about $1000 and I did all the work myself. A 2.5L will cost a bit more as you'll have to buy aftermarket forged pistons and rods instead of stealing them from a junkyard turbocoupe like you can with the earlier 2.3L rangers.
(fun to drive around with the turbo)
