Hi David:
Try Jim Fraser in Arnprior (Fraser's Garage) as I heard he has a set of 9.00X13 sand tread tyres.
My C8 has Isreali made implement tyres on it. They spin on damp grass but look pretty good. They are quite rigid, 8 ply if I remember right. Another source of 9.00X13 tyres is aircraft tyres but they cost a heap unless you can find cheap blemished or used ones.
Brian Asbury has the rubber armoured marker lights for about $40 each.
Shock absorbers are likley bog standard 1940 Ford pickup parts. Check with any antique Ford parts dealer after you measure the mounting sizes and the distance from axle mount to frame mount.
While rebuilding an engine can be costly, if the numbers all match and you have the original engine its worth the effort to keep her all together.
Sounds like you'll have this little girl up and running for next years' season!
Mike