Wow, this is pretty much the same problem I'm having - Hopefully someone can give me peace of mind before i try bend my new old Bianchi. Here is the situation:

Picked up an old 80's Bianchi 12 speed which was in mint condition. Don't like riding on tubular wheels so I bought a new pair of wheels and a new shimano 6 speed cassette thinking I would be riding tongiht. Not.

The front wheel went on fine, got to keep my original Campy skewer. The back cassette went on fine with 2 x 2mm spacers. I then go to put the wheel on the bike and I find that the back hub is too big for the dropouts. Its just a little too big, im assuming it takes 126 and this new wheel is 130.

I realized I;ll have to get a larger skewer but my wallet is dreading buying a new wheel. Its cool to just give it a heave and let it pop in? This isn't going to bend the frame and wreck the bike?

T