"A" sheetmetal assistance....

[INVISIBLEKID]

Working on the roadster a lil today,and have a few Q's regaurding the rear "wheelwells". Mine we're too tough to save=anything. I have new/aftermarket pannels to install. I cut out the old stuff,and left a 1/2'' lip.(pics). I will still have to trim the new pieces accordingly. My Q is- do (you) fit and overlap,finnish weld,clean,and call it done,? OR,fit,tack,and grind through for a gap,then weld? My car will be fenderless,so i'm thinking the latter,which is no prob.Won't be shiny black,and more of a survivor,but want to do it right,and not be hack.....
Any help appreciated.......Kid