On my website I have a blog on this subject that you might find of interest. I wrote it on 11/1/20. You can visit
www.markearzoumanian.com. and then click on the "Love of the Hobby" section. It's about my firsthand experiences converting GAIs to PSAs.
NEVER submit a slabbed GAI to PSA. I broke all my GAIs out before submitting. My experience was that while there were a few smooth transitions (i.e. GAI 4 to PSA 4), most PSA grades came back LOWER than the GAIs. Good luck.