Will you be using EFI or a Carb?
'88 Ranger should have 2 fuel pumps, one in the tank and one in the frame rail under drivers seat, these will provide 40psi pressure and enough flow for an unmodified 5.0l V8 using EFI from '97 and older Ford, these used return type system with fuel pressure regulator on the rail.
If you have a newer EFI then you will need to change the pump on the frame to a higher pressure pump, 65-70psi.
If using a carb just use the in tank pump and delete the high pressure pump in the frame rail, the in tank pump was from the '83-'85 carb days so will work as is with carb(6-9psi), Forded added the second pump for EFI(35-40psi), '86-'88, until newer higher pressure pump could be added in the tank in '89.
From article in engine section:
Accessories:
You can use a factory V6 Ranger alternator with a V8 bracket and adjuster. The alternator-mounting bracket is part # E7TZ-10A313-B and the adjusting bracket is E6AZ-2888-A. The stock power steering pump can be used on a V8 with the correct brackets found on many Ford passenger cars. The power steering bracket is part number E7TZ-3C511-A. You can use your original temperature and pressure gauge but will have to re-calibrate your factory tachometer. Contact Specmo Enterprises (810-398-9103) about recalibrations. You can use your air conditioning with the proper V-8 brackets. The wiring will need to be extended and the condenser will have to be relocated to the front side of the radiator.
Whole article is here:
http://www.therangerstation.com/tech_library/V8Conversions.shtml
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