You should build it. And there are a few important modifications you should make to the 727 that the 904 does not need.
You "probably" would be better off with a manual valve body and bolt in sprag at the very least. The 727 does not need to do burnouts on the 1-2 shift as if the tires grab on the shift to 2nd, it can cause some serious damage if the tires bite really hard on the shift into 2nd gear.
If the manual valve body is not something you want to do, I would advise the 904.
All this said, millions of 727s lasted on the street with zero trouble behind mild to moderate engines. It's just something to think about.