Many of his songs are best played in open C (CGCGCE) plus capo e.g. Singing Land, Caledonia.

Others also work in this tuning e.g. Until We Meet Again, It Fascinates Me.

Rescue Me is in DADGAD (although works nicely in standard tuning too).
His version of Green Grow The Rashes is also DADGAD, although I prefer to use (cause it's slightly easier) DGDGAD.

Trail of the Survivor and Turning Away are both easy in standard tuning,with a capo at the appropriate fret, as is This Love Will Carry, and High Flying Seagull is in Standard tuning .

Ready for the Storm is easiest and sounds best in Open Cm, but not quite as described above, better to use C G C G C Eflat. However, it can be played in standard tuning, although it's pretty trickly unless you're good with using your left hand little finger for pull-offs and hammer ons!

Let me know what song(s) you wanted and I'll get back to you on the appropriate tuning.