So far it's going slow, but for now here is what I can offer:
1) Ball pythons have been born with enlarged hearts before... the stomach is something I haven't heard of before but not a unique case I'm sure. From my findings snakes with enlarged hearts can live for quite some time. One research article said that a pair of BPs being study lived to grow "several times their original body weight" though it does not mention a time frame :/
2) A python's heart can increase nearly 40% it's original size 2 to 3 days following a meal. All part of digestion. That considered I would ask you to consider undersize prey items when your BEL is ready to eat so as to make it easier for the lil worm.
I can post links to where I found this info if you're interested. I'm still doing some research, I'll share anything new that turns up.