Ummm, yeah; thats me!
Triumph rod size would be fine, as I say, only 1/16" smaller.
But Musky's right, dont make it any smaller than necessary.
We're using triumph size because of the 89mm stroke crank - we're hoping to minimise crankcase clearance problems. The slightly smaller size buys us a bit more room.
No worries about strength as we're using a billet crank and rods.