Sounds like you know what you're doing. I was concerned for a minute. Most of my bikes are old. I've got 4 Schwinn Continentals and a Suburban from the 70s. And a newer (90s?) chromo Univega.
I'm pretty confident of their condition because they get stripped down completely, to the smallest part. I clean and regrease everything.
Of course, the failure of a part wouldn't usually cause a catastrophe. Frame and forks... With these old steel bikes, if nothing is noticibly bent or cracking, then they will probably last forever. Seat post... unlikely. Handlebars... should be OK as long as they are not made out of copper (haha). The only other old parts I worry about are axles, especially the front (ouch). But like Toytime says, old parts are probably stronger than the new Chinese stuff in the stores today.
My motor only runs me about 50% faster than leg power, so a wipe-out might not be that much worse. On the Simpson's, a motorcycle daredevil told Bart, "Broken bones heal; chicks dig scars; and America has the best healthcare system in the world".
So ride that thing!
P.S. I wish I could find bikes like that around here.