Try
www.digitalcorvettes.com They were way more open to modding Corvettes. I haven't been by there in years though. Many of the people that started that forum got sick of the attitude prevalent on corvetteforum which you've already experienced.
As for your question, the answer is yes, you can do the swap fairly easily but the entire front clip has to be changed. Everything from the windshield forward. You could graph the 68-72 front fiberglass onto the 73 front clip. To be correct though, the front clip is different. Pretty much anything you might need is reproduced or available from junk yards. The question is budget and time. Sounds like he's going to be putting a lot of both into the car either way. I agree he might as well build it how he wants. However, I would suggest he keep his eyes open for a 68-72. They can still be had in good condition for reasonable prices. If he's patient and willing to travel, he can pick up a complete and running 68-72 for about what it would cost for just the fiberglass parts needed to fix his 73 if he's looking at buying new panels.
Also, here's this in case he might be interested. Supposedly, it's solid, complete, and undamaged.
http://fortcollins.craigslist.org/pts/4627669018.html
Here's where I found the link
http://www.digitalcorvettes.com/foru...d.php?t=223842
Oh, one thing to think about is that the 68-72 had a separate wiper door. The hood didn't come back to the cowl. That wiper door is operated by vacuum just like the lights on the car. It's a pain in the butt. It looks great but it's crappy. I would find a way to convert it to electric if I was going to have it on the car. Or, just don't ever drive in the rain.