I say spend the $10 on the parts to fix the thermostat and put everything back to original spec. I did that job on my '87 wagon with dealer parts about 11 years ago, and it is still running just fine.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC