TODAY is a Great Day to visit our Store and order the parts you need for your truck ! ! !
Talking from experience, probably will burn the clutch trying to get that combo moving if you have a 2.73 gear like I think you do.
im going to add this. we've towed a car trailer and another lwb. with a blazer on 38 with no issues. and sm465. dont think it had 2.73. http://forum.73-87chevytrucks.com/smforum/index.php?topic=33169.0
Be more like 5000 lbs. C20 would do better but a 3.73 or 4.11 would be cheaper if you like your truck and don't do much highway driving