63-66 idler arm conversion to late model thru bolt ?

I broke a steering mount almost off a k member in my 65. Not sure what happened but at about 10 mph the entire front end started shimmying like a bad grocery cart wheel, vilolent back and forth about 10 times a second! I 'but **** myself. I pulled over and slowly accelerated again and 10 mph bam! Limped it home under 10 and when I got it home and jacked up. I noticed the steering mount cracked through in 2 of the 3 welds. Found another 65 K 400 miles away, road tripped it and replaced it. Didn't think to save the bad one to weld it up and gusset all the points.