Chase + Time Machine idea is kind of off since Chase actually gave up the chance to use Gert's parents time machine to undo her death back in Joss Whedon's run on the comic.

And trying to change the past via Time Travel in the Marvel verse is iffy at best. Some people can make it work for them like Kang the Conquerer, others can't like oddly enough, Kang again (teenage Kang).