@D4v1d
Your 4.0l is an excellent candidate, especially if it is the California SFI version as it is 10% more efficient:
+20hp, custom regrind cam
+20hp, flow bench port and polished heads to intakes
+20hp, quality headers with appropriate sized free flow exhaust
There is a bit more power that can be realized without using forced induction but at the end on the day it is a truck engine, design to perform as a truck is be expected; ample torque to get payloads moving while being drivable:
• increasing the compression ratio will yield 4-6% more HP per full point of compression
• a multi-spark ignition will deliver 3 or more high voltage sparks below 3,000 RPM
• a capable set of plug wires
• an electric fan will reduce the load on the engine
Some consideration should be given to maintaining normal engine temperature:
• remote engine oil filter
• engine oil cooler
• lower heat range spark plugs
What is your intended use?