I didn't use a puller when I worked on the front of my '96. But I'm not familiar with the earlier C4's so they might be different.
Did you try tapping it off with a soft hammer and/or 2X4 yet?
Jack up the engine a bit to help clear the cross member. You should get enough clearance without breaking loose the motor mounts.
I don't believe the balancer is a press fit, rather a tight fit and the corrosion that occurs over time is what keeps the pulley anchored once the bolts are removed.
I did spray the area with PB Blaster to lube it up a bit.
The balancer came out and went back on without any major antics. It did require indexing the crank to certain positions in order to provide clearance. I used an impact gun to remove and apply the bolts. Also, there is an embossed diamond indexing mark on the pulley/crank so it goes back in the same position it came off. Clean off the I.D. of the balancer and the O.D. of the shaft and apply a light grease to retard future rusting. Keep the bolt threads dry.
I also did a 1995 Z28. Similar engine as a Vette, but tons more room to work. I did use a 3 jaw puller on that job, but once the rust seal broke it came right off, too.
Good luck...
-- Mark
The 1986 damper differs from the later models. It is pressed on and you cannot use a three jaw puller because the outer rim is bonded to the inner section with elastomer. Pulling on the outer rim with the three jaw can separate the rim from the hub and ruin the damper. I have removed them with the engine out and it as a simple process. More difficult in the car due to the lack of space. I have a more compact bolt on type puller coming this week, it's a little more compact than the one I have. Hopefully that will do the trick. I'll keep you informed.