Tools to stich photos

Map
of existing land use in the County of Cumberland 1945

A very helpful man from the Critical Mass list took a bunch of photos of a map I've been hunting for. The map is Map of the County of Cumberland showing Interim Plan No.2, 1947 from the NSW State Records. I want this map because it demonstrate's how the RTA (then DMR) has been hell-bent on implementing this ancient plan, which was conceived as Sydney's answer to LA's freeway network, before LA realised you can't build your way out of traffic congestion, which is something the RTA hasn't realised yet either.

So he's taken a big swag of photos with a digital camera of this very large canvas-backed map. Of course all the photos are at different angles, with different light and with differing perspectives. I need to stitch these together.

Hunting around online, most of the tools seem to be designed to stitch together linear panoramas, taken from the same vantage point and with very similar perspectives. Not useful for this job.

So, lazyweb, any ideas on the best approach?

PS: The photos are already in the public domain, and my stitched-together version will also be.