you need to rivnut the top one and one of the side ones or you wont be able to get the prop in and out without moving the engine forward or taking the diff out.
trust me been there done it got the t shirt
also when i did my side panels i just copied the drawings from the book on to the ali sheet then cut it out. they fitted perfectly. the only holes i had to make bigger than the book drawing were the upper wishbone holes closest to the back of the car (just so i could get the plastic nut covers on) and i had to widen out the steering rack holes so the rack gaiters didn't catch.
think that was it.
considering Chris just drew the side panels on the pc and never actually made them to the drawing for the book car i was pretty impressed that they fitted first go. (yes he told me this after i had cut the panels out lol)