OH MY GOD!!!! It's a miracle that bike hasn't disintegrated into a smoking pile of parts on the floor!
Seriously, what is it about those welds that doesn't look right to you? That's what mass production robotic welding looks like. It's the same on all of our bikes and we're all still alive.
If you have a chance to buy a K5-6 1K in decent shape and running condition, do your usual due-diligence, then make sure that the frame brace and master cylinder recalls have been done. These are arguably 'the best' 1000s Suzuki made. 366 lbs, 180 hp, no cat, no nannies.... just a slipper clutch. Not to be passed-up.