The Subaru goes together a little more easily than what I work with then. I always find the piece the rest of the car was assembled around. I counted one day when I noticed how many panels come together along the A pilar between the windshield and the floor board, and came up with eleven that I could see, all held together with spot welds, and many of the plug welds were in areas that I couldn't spot weld or get a wire feed tip into.
If you are planning on plug welding, I suggest at least doubling the number of spot welds and seam welding after, or buy a spot welder and run one spot weld every inch. Short of seam welding, you will never match the strength of the hight voltage robot spot welds on the assembly line and bonus strength in that area is more valuable than anywhere else.
I keep reaching at the door panel to shift with my right hand when I drive RHD. Each shift takes about 30 seconds to realize I am using the wrong hand, then locate the lever with the other wrong hand, and complete the lever movement. But it feels slower than right handed shifting, even when I do remember to use my other wrong hand. With all the importance placed on speed of shifting and short throw shift kits, that fraction of a second for each shift times the number of shifts in a 20 minute heat might add up to several seconds of lap time.