@Jerry Dean ,
Great, then you see that increasing the displacement by 1.25% should yield 2hp +/- while increasing the compression ratio a full point can offer 8hp +/- (a 400% larger bump than the displacement ∆). Additionally 2 or 3 compression points are not out of the equation since stock is 9:1:
• a 0.035 head mill will yield a point
• 95-97 fastburn combustion chamber heads or 98+ fastburn combustion chamber heads will add a point, from your 93 slow burn combustion chamber heads
• Ford SOCH 4.0l flat top pistons will add a point
Those 3 options are all affordable and compliment a rebuild as these Cologne 60° V6's do respond well to a increase in compression; just take into consideration the extra heat that the process will add and take proactive steps to control it:
• add an engine oil cooler
• 1 or 2 range cooler spark plugs
• exhaust jackets on headers or exhaust manifolds
• improved cooling radiator
• stainless steel cooling hose
• improved flow exhaust system
I use all of the above.
NOTES
* If you want a little more useable power after your rebuild, then lose the crankshaft driven fan/clutch for a 15" electric fan; it doesn't make more power but it does reduce the load on the crankshaft...it makes a noticeable difference driving and at the gas pump.
* synthetic fluids offer another potential reduction on the engine load.
* you may want to consider an aftermarket multi spark ignition, if your not make a street racer, then a multi spark will have a lot to offer your OHV 4.0l at engine RPM below 3,000, where it will live almost 100% of the time.
* K&N offers a 1 million mile warranty on their air filters, making a drop in K&N, at least practical.