Shaved Engine Bay Corner Seam Finishing

[RSchofield10]

Good morning,

I am in the process of shaving my engine bay. While most of it is self explanatory I do have a question regarding finishing inside seams. In the photo below I plan on welding all the highlighted (green) seams and then grinding the welds with a die grinder. My question is how do I achieve a smooth transition at the 90 degree angles as in the second photo below? Would the proper procedure be after grinding the weld to add minimal filler and sand with round block or perhaps seam sealer?

 

[OJ86]

I used to weld them all the way around. Then I just decided to tack them say every 2", and then panel bond the seam smooth like I was caulking my trim work in the house since I'm a terrible carpenter.