Pin 1 pic only needs the 3 pins welded at one end because the other end of the pins are inside a hardened surface.
Pin 2 pic needs welding at both ends of each because both surfaces are just mild steel & all 6 holes will elongate. The 3 dowl pins won't be needed.
Pic 2 was a GTA runing E85 btw
Cheers - Aldo