My '90 SC had a 3.54LS, and was in bad tune - compared to my '91, REALLY bad tune. I towed a '48 Ford Club Coupe on a car hauler, 5,000-6,000 lbs, and had no issues. I say install the 3.54 gearset and a turbo!
That motor can take 2800-3000 RPM just fine, although it's not at peak efficiency.
Eli