Just returned from a wonderful visit to Colorado. Vance Jct., Como, Platte Canon, Durango, CRRM, Sublette - never enough time to see everything.
Anyway, 20's test coupons were on my desk and stress relieving increases the strength of the frame metal by almost 10%. The old material failed outside the weld in both cases. Prior to going to Colorado I cobbled together a wooden binder using the CNC and a specific measuring system on the frame lugs. Oddly enough, it worked really well and should speed up the laborious task of fitting the binders.

Wooden binder in the mill.

Wooden binder on first fitup.

Test coupons. The closer one is as welded - failed at 39,406 psi; The other one failed at 42,866 psi. Both failures in parent metal.