I know everyone has an opinion... and I'd like to hear some of them!

I'm a first time buyer, and I've come across a 172P for sale at a
local airport. Its a 1981, 4000TTAF, 1700SMOH. No GPS, standard
avionics (digital radios, 720CH, ADF, Audio Panel, Xpndr) No damage
history and a current annual and IFR certification.

It looks to be extremely clean inside and out. Paint seems to be a 7
or 8. It is privately owned, although I don't know about rental
history in the past.

The owner is asking $57,000. My thoughts are that I could but a
Garmin 430 for around $4k, (how much would installation be??) and in
300 hours I'll need a new engine. After a $20k engine swap, will it
be worth $77k or more with 4300TTAF and 0SMOH?

Does this make sense as a first airplane, with times like these, or
should I look for something with lower times and a GPS already
installed?

And finally... does the price seem reasonable as is, or should it be
priced lower due to the engine time?

Any help with this decision would be immensely appreciated!