http://www.ebay.co.uk/itm/Haynes-Roadster-Chassis-Locost-Project-Barn-Find-Lincoln-/111613119858?pt=LH_DefaultDomain_3&hash=item19fca90d72

Could be a very good starting point at this price depending on quality of fabrication?

The welds look shite, no penetration at all on the ones I can see, other parts still look tacked. nothing a good shot blast and grind couldn't fix in an afternoon.

For that price though, and the amount of work needed to get it welded right, I'd be scratch building from new stock.

I'd second that. To be honest I would buy a pro made chassis as a start point. The amount of time it would save you would be worth it.
If you are a good welder, a flat pack version is worth considering too.

I'd just buy the tube, or a pre cut tube kit. IMO it'd be quicker and easier to build from scratch than try to sort that out - also then you know there are no surprises waiting for you!