Locked Up!, What might it be? Options

[74914LE]

Just finished getting a 72 1.7ltr. ready to start up after sitting for 29 years. Went over everything in the fuel, vacuum, and ignition systems. It turned over just fine without spark hooked up to it. Now for the moment of truth. Made sure I had fuel pressure and attempted to start it.

After about 3 tries, it fired up and started running!!!! After about 20 seconds, a rattling sound started, then got worse. I immediately shut it off. Then tried to turn it over again, and it would not turn over. I then got it on jack stands and blocked one wheel to put it in gear and see if I could spin the motor by hand with
transmission in 5th gear. The wheel will turn about 1/3 a turn in either direction and it locks.

Before I drop the motor and pull it apart to check for a dropped valve or worse, though I would see if anyone wanted to weigh in on what this might be....ideas?

Thanks in advance!

[74914LE]

On close inspection, this is what I found in the photo below. #2 INTAKE pushrod is bent. Any idea what might have caused this situation? I pulled the engine this
evening, and will start pulling it apart tomorrow. Curious as to what I might find...

[JamesM]

When you turned if over before starting it up was that by hand or with the starter?

I tore down an old 1.7 where a couple of the valves had completly seized in their guides after sitting a long time. Guessing valve seized for whatever reason (crud or dropped seat maybe) or the pushrod sliped out of the rocker and jamed.