There is no comparison in strength between a 400 and a 727. A 400 is much stronger, more reliable, and much less expensive for any given power range. I have a couple expensive 727's. They're fine at the 1000hp mark, 1200 starts to wear on them quickly, and forget big blower power. For half the cost of either 727, my 400's are rock solid at 2000+. I beat the cowboy p#ss out of one of my stock case 400's behind a blown 572 alky hemi in a heavy car for 2 years, after running it in an NA car for 2 years prior with no service. Took it to Neal trans (original builder)here in ga to get checked out before it goes behind a meaner blower. He dropped off at my house yesterday with a total bill of 500 bucks. I said I'd be over 2000 this time, and his response was keep it under 2500 or we might need a better intermediate shaft than the one you have.

Maybe someone runs a 727 at 2000hp, but I've personally never seen it, and I'd bet it would be way way sketchy, and need lots of care.

All that said I like my 727s for their purpose. One is a 727 specialist that is a great trans, and the best one I've owned. The other is a cope racing one that is also a great trans with zero complaints. I run them to keep one car all mope. Otherwise I'd run nothing but glides and 400s.