You are so right, Bob. We do live and learn. The flange on my jack is just barely too narrow and I thought there would be enough bite to hold, but it slipped, and fortunately it caught on the power steering. The jack goes low enough for now, but when I lower the coupe some more I'll have to drive it up on blocks to get it up so the jack will slip under. I think I will take the jack to my local welder friend and have a steel plate with ears and wide enough to span the crossmember welded on. I dodged a bullet this time, but I might not be so lucky next time.
Thanks for your info.