Sorry, just saw this question. Just cut the ends off and use it like any other chunk of 3" c-channel. Also left some as is and used for pallet racking of course.
From awhile back but got an old beat up wood bench at auction that someone had added 1/2" steel plate along with some plastic that warped after left outside. The steel had a bad cup of 1/4" over the 6 ft length when unbolted
View attachment 69574
So took the steel plate and squashed it between a couple heavy i-beams to flatten it and welded the c-channel to backside to hold it flat. Turned out decent. Less than 1/16" bow now more like 1/32".
View attachment 69575
The vise is an old Reed model 104 that found a date of 12 (Dec) 22 (1922).