C4 Vette IRS Load Capacity

[OldSchoolSS]

Hey guys,

I have a 65 Buick Riviera and I want to put the front and rear suspension from a 90 Corvette under it. The car "should" be around the same weight as an Impala when the heavy Buick drivetrain gets replaced (3400-3600lbs). I'm worried that the car might be too heavy to put the IRS under. I know it will be fine for daily driving, but if I have 4 people in the car and a trunk full of luggage on a road trip I don't want something to snap back there. Does anybody know how rugged these rears are? I plan on making a coil over mount that ties into both the shock mount and the leaf spring mount on the rear knuckles (spindles, or whatever you call them on an IRS). I've seen them under trucks and nomads, but a lot of them are trailer queens that rarely see a driver let alone passengers.

Thanks,

OSSS