HELP! I bought a mess?

Those are the factory “low performance” springs.
340’s used red springs.

Those heads most likely came off a 360-2bbl.

In theory, a 67 273 would have a solid cam.
Do the rockers have some lash?

If you’re pulling the motor anyway, the “what I would do” answer is find a 360 and freshen that instead.

You could have the new motor all done and ready to go before disabling the car.