2004 Dodge Durango Windshield Cowl

Sorry for my wordiness. Scroll down to the "***" if you don't need background info.

I am in the process of buying a 2004 Dodge Durango SLT with around 140K that is in
"exceptional" condition, according to my mechanic. Pre-purchase inspection suggests
everything is in order, the only thing is that the spark plugs are "long overdue", but shows
no sign of misfire and are undamaged, just old. The mechanic said that they were "factory
plugs" so I don't know if that just means it hadn't been tuned up since the warranty
expired, or if it had never been tuned up ever.

Given the reputation of the Dodge Durango 5.7 Hemi, I figure the old plugs is a good sign,
actually, and indicates that there hasn't been prolonged, ignored problems.

There was no audible knock, no codes, chassis clean, solid straight and rust free, The
transmission was "damp" - which is common with older cars- but does not slip  and is
otherwise ok. All four brakes have been recently been maintained, and this seemed to
stand out to the mechanic.

Interior is like-new, not a speck of damage to the upholstery. Even if the plugs had never
been changed, it seems the previous two owners did take some degree of pride in this
vehicle (though, the plugs thing does worry me, and should, but the drive train appears to
be in working order). I know that the vehicle engine "fail without notice" but aside from
severe and sudden hydrolocking, I do have a hard time really believing this.

The infamous windshield cowl seal is warped, and I *do* plan to replace it with the
updated cowl as soon as I purchase the car. I play to have my installation inspected by my
mechanic, if not professionally installed, So I am aware of this issue.

It seems that the problem with this particular vehicle is the hydrolocking. If I replace the
cowl, will the engine be as reliable as any other of similar milage? I have heard of inherent
flaws to the lifter design and materials used, but this does not seem to be a widely
accepted position, and the issue with the Durango seems to be mostly with the cowl
design - and frankly, this assessment always seems a bit like fanboy BS, especially since
other vehicles with this engine don't seem to have such a reputation for failure. (and as
such, if you just 'don't like' dodge, please refrain from answering, thank you)

***

So just to recap, provided that the engine is in good working order at present, can I expect
the most problematic issues with this vehicle to be remedied by installing the improved
cowl, or are there other inherent problems with this engine?

Also, what is the prospect of codes being present when leaks are presented to the intake?
Certainly a misfire resulting from water in the engine would be recorded, right?