^ This thread is so old that I hadn't even moved here when it was active. Meaning I didn't have easy access to my 240s, one of which was still at Egads' place....
Since then of course, I've moved states, got all my cars onto one property, swapped over the front end on the Rudie GT to the 82+ style, and removed a round headlight front end from a '78 parts car and sold it on. And learned from the experiences.
No, it's not exactly a bolt-on / bolt-off operation; yes, there are a couple of spot welds which hold the front fenders to the valence panel assembly. Sometimes they have been pop-riveted together or held together with a self tapper instead of being spot welded.