[Cougar]

Having both IRS and more recently a 3-link, no question, definitely go IRS. I definitely prefer the ride of my high revving 347 IRS over the buckboard 3-link. The only advantage the 392 3-link has is in manners, with the very mild cam and big low rpm torque, she'll putter happily down the road at as little as 12-1300 rpm. Torque is nice, but in cars this light horsepower is in my humble opinion a better choice. If you like smoke shows go for the torque and solid axle, but if you want a fast sports car go for the IRS and build that motor to rev!
Over the winter, I plan on putting my IRS 347 back together with the following changes;
1) Remove the ps and install an 18:1 Flaming River.
2) Replace the Vic Jr manifold with a Perfomer RPM, the Vic has NO low rpm manners
3) Have the tranny rebuilt by Astro, and lower 5th ratio to .79 (3.27 rear).
4) Definitely sticking with the 15" tires and power brakes.
5) Adding a vacumn guage in the dash.
Just my preferences, but maybe this will help in your thoughts!
Peter