Here's a thread with a little info about a 250 six that came available in '67. Not sure if it will bolt in, maybe someone else will know.....
http://www.clubhotrod.com/t11915.html

By the way, what does the wife have against a small V8? Chevy offered a 327 dealer installed option in '62. I would think that something like a 305 with attached auto tranny would be a cheap alternative. Do a search for "Nova V8 swap".