I have an old (and beautiful) 1993 Paramount Series 3 lugged steel critereum road bike with 126mm spacing on the rear dropouts. I am able to put a modern (130mm) wheel set in the bike. It should not work, but it does. To do the job right, I would have to send the frame to Waterford, and they would replace the bridge and align the lugs. I probably will never do that, it is just not worth the money, and it would cost a fortune to get the paint job restored.
So you might be able to squeeze a modern wheel in your frame. If that does not work, you can try to convert your new wheel to fit a 126mm spacing. You should be able to put a 7 speed free hub body on your new hub, and get it to work in your frame. If the dish is off, your LBS could fix that. I am not sure if a shorter axle would be required or not.
See Harris Cyclery for details on free hub bodies.http://sheldonbrown.com/harris/k7.html#bodies
They have 7 speed cassettes too. When I still ran 7 speed on my Paramount, I was successful at adapting 8 speed cassettes by leaving the end gear off. That is an option if you don't like what Harris has in 7 speed cassettes.