If I am reading this right, the connection was always at some level of risk, since
the flights were separately ticketed. You don't say if you are checking bags, but
that would obviously add more time/risk to the schedule.
If this is incorrect and your flights were all on one ticket, then you should indeed have
the airline reticket so it's all on the same ticket. If the inbound flight is delayed, you
will at least get protected and not be penalized for missing the second flight.
If this cannot be done, and you don't want to fly into Paris the night before, as others
have suggested, then (with an eye out for any transit strikes) you need to either take
the RER to Orlyval, or at least have a way to check Paris traffic to be sure you don't
hit a major traffic jam. I realize that you said you don't want to take the train, but
under normal circumstances it will be the most consistent and reliable method to make
the transfer. If you have a lot of checked bags, all the more reason to fly in the night before.
I doubt anyone would argue that 7 hours is enough to make the transfer if everything
is on time. It's if things are not on time that you are at risk.
Lastly, if your original flights were all on one ticket, then I'd submit a claim to the airline
for your transit expenses, at least between CDG and ORY, and maybe even for the hotel
if you fly into Paris the night before.