Sprocket spacing question...

...bear with me, here's what i'm planning!

I've a 126mm rear-end spaced Peugeot Athena 653 frame which i'm going to run with a modern campag groupset - 10 speed Veloce probably. I'm going to use modern 130mm spaced Ambrosio campag-alike hubs (they fit in the frame just fine!) but with a shimano freehub. I've got tons of sprockets from cannibalised 7 speed shimano cassettes and I make up my own ratios you see.

I'm then going to buy a Clarks or Miche campag compatible 10 speed cassette - I understand these can be split apart and that you get all the spacers for campag sprocket spacing. Is there any cheaper way to get a set of campag spacers?

I'm then going to use my stock of shimano sprockets on the shimano freehub but using the campag spacers. I'm not bothered about 10 speeds to be honest, so as many of these sprockets and spacers as will fit will be fine: how many would that be do you think?

If I need a narrow chain to suit the narrow 10 speed spacing, will it work on 7 speed sprockets? Am I right in thinking that 10 speed sprockets are the same width as 7 speed, its the spacing between them that differs (and the external rather than internal width of the chain)?

What else is wrong with my dubious logic ??

Assuming you want 10 speed why not use a 10 speed Ambrosio cassette. Shimano splines with Campag spacings.
Bear in mind that each "speed" spacers and sprockets are different. Each manufacture is as well. The spacing for Campag and Shimano works as 7 speed Shimano and 8 speed Campg (5mm) but seperates there. Have a look at Sheldon Brown http://www.sheldonbrown.com/cribsheet-spacing.shtml to start with.
That's Ambrosio cassette will be the cheapest method and give you perfect shifting. Bodging is fun but if you are starting fresh stupid. You could of course buy Campag spec hubs if you haven't bought already

Ambrosio Zenith/ Novatec hubs are available with a Campagnolo freehub or you can buy a spare.
7 speed sprockets are too thick for a 10 speed - the chain will ride on top of the sprockets and shifting will be very rough