Nice progress. Your welding is plenty good enough for a skim coat of filler when done.
You can use a 'regular nut' and then just tack it in place after it's bolted down. Not as fancy as a floating captive nut, but it'll make subsequent removal/installation more fun. Use anti-seize compound on any underbody/roll bar type threads.
You can use a 'regular nut' and then just tack it in place after it's bolted down. Not as fancy as a floating captive nut, but it'll make subsequent removal/installation more fun. Use anti-seize compound on any underbody/roll bar type threads.