That's actually why Nantucket ignores meter for now - cmudict's stress patterns are really inaccurate and unsatisfying. espeak is an interesting idea!
One thought I want to explore in a later version is using cmudict's stress patterns for polysyllabic words, but ignoring any stress/meter rules for monosyllabic words. I suspect that'll do pretty well, and it'll be interesting to test it out.