"My husband is happy with it, so that's what matters most."
Well, I won't quibble with that attitude, for sure. Anyhow, a 6' blade is fine, as it will extend beyond the tracks of your rear tires, and will, for the most part, not pick up more debris than your tractor can handle without loading the tires or some other approach to putting more weight on the treads (if turf tires, forget the above comments).
You'll find that traction is lost way before the engine is challenged. I've a 6' box blade on an
L3410, and it's a good match unless I get too much wet sandy stuff in the box - then all that happens is my rear wheels spin (yeah, despite switching to 4WD and locking the rear axle), easily handled by dumping a bit of the load. If you've just a simple blade, without the box, no problem.