The mechanic which built the motor gave me a call. The motor was built prior to my purchase of the car. Here are the details: rebuilt @153k miles, GM replacement short block (109) , 200/ 200 roller cam, heads and intake ported, other mods double pumper in the tank, in 2004 a/c (compressor, lines, and dryer) replaced, new power master and brakes.

Only 547 GNX's were built in 1987, it's only year built.  As with most muscle cars during the last few years, prices have increased dramatically.  Just turning 20 years old this year, the GNX is the ONLY car built in the 80's that has the highest chance of bringing 7 figures in the near future.  Drive it the way it is and then restore it when you are ready to cash in.  With most GNX's in the hands of private collectors for the past 20 years, the GNX is a car you really never see for sale.  And when you do, those low mileage museum pieces are bringing over $100k in today's market.  As you can see below, this GNX 107 is somewhere between Low & Average Retail.  As the saying goes, anything is for sale for the right price.

With that being said, most likely I will hold on to this piece of automotive history to pass onto my kids in the future.  My first car in High School was a 1982 Buick Regal Limited Coupe.  Back then I had always lusted after the Grand National and the TOP DOG Buick GNX.  I do remember when the GNX came out, no one could buy one and if you could find one, it was marked up 2, even 3 times its sticker price.  547 were made, something like 525 were only sold to the public as GM kept some in their corporate holding spot.  And over the past 20 years, some have been "totalled" by accidents & unfortunately some have been stolen and shipped out of the USA.  So the POOL of GNX's actually out there is most likely below 500.