Keep my 94 Subary Legacy or buy 1999 Subaru Outback

I currently own a 1994 Subaru Legacy.  The odometer stopped working
years ago.  I have maybe 240,000 miles on it give or take a lot. It is starting
to be less reliable, and I need a reliable car for my job, more info on issues
at end of post.  I am doing 300 miles of driving per week, a mix of rural
mountain highway, dirt road, and city driving.  Not being able to use my car
for a day of work, getting a different car to use, transferring over all my
equipment,  taking my car to the mechanic, picking it up, transferring
equipment back it a BIG hassle.

A friend has a 1999 Subaru Outback with 180,00 miles that has been VERY
well cared for, and garaged.  The engine is the EJ25D type, which I think is
the type that has head gasket issues.  If the head gasket was replaced, do
you think it would be more reliable than what I have?  And if so, what would
be a fair price for Missoula, MT where Subarus are loved?  

Problems my car is having:  
ORDINARY STUFF - Radiator and brakes replaced.  Blower motor
replaced.  Automatic steering filter needed cleaning.  Wouldn't start,
probably was road salt on spark plugs.   - All fixed.

INTERMITTENT STUFF - All of a sudden, less power for a minute or two,
needing to pres harder on the gas. Doesn't repeat for weeks.  Sounding a
bit whinier than usual for a few minutes or a few seconds here and there.  
Burning plastic smell for the first 20s I use the AC, about half of the time.

MORE BLOWER MOTOR - They put a new one in this winter.  It worked for
a while. Then it stopped a few months later.  They said it was a wiring
issue, fixed it.   
I didn't really need to use it mid-spring, so I didn't notice any issues.  When
I tried to use it later, it has a burning plastic smell the whole time I used it.  I
made do with opening the windows until I could get it in to the mechanic.
It didn't make the smell for him with 1 hr of driving and multiple attempts in
the shop. Now for me, it only does it for a short while.  However, the AC
only cools the car half as much as it used to.