300K is quite high.
well maintained the motor is capable of 500K plus... yours seems to have records, you should verify the records match the vin on the car, then look them over and see if the coolant was maintained regularly and see if the head has been replaced with a more recent model like the 18 or 22...
the motors are readily available to replace if you do run into problems. I would test drive it, and have it inspected for compression, and blowby.
the price is not bad. so cal cars are highly sought after...
good luck, and welcome to the forum!

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!