I'd want to have remaining cash sufficient to meet my spending needs. If you are in the planning stages, I'd look at them separately. Say, with the property taxes and upkeep of a house, but assuming no mortgage, you need $750k. Then, i would separately figure out where I wanted to live and how much that cost. If you are happy with a $125k place, then your overall number is $875k.
If I had to guess, I would probably not do more than 20% (house / (house + remaining stash), but I'm a ways a way.