In my experience, the combination of rounds was dependent not only on the pilots preference, but also on the type of mission they were going on. You wouldn't necessarily arm AP-incend if you were going on an escort mission, but would if you were going ground attack. As a general rule, every fifth round would be tracer. What goes between them is a matter of debate and conjecture. Whatever you do, I am sure it would look great.
I attach two pictures of a small grouping I made up of ground dug 50s, married with authentic WW2 links, along with what the 50s looked like before I 'cleaned' them. Each spent cartridge was married to a head and then cleaned, with each example taking about one hour EACH to get back to this shiney condition. Lots of grinding paste, flap wheels and polishing cloths were used ! Makes a nice talking point and was due to me wondering if you could take ground dug relics back to 'new'. This is the only time I've done it as I prefer my relics to be that.......relics.
Cheers
ww2digger
PS The tips were painted by me on standard ball rounds........they are not incendiary or AP so don't fret ! They are also totally inert and were made up of spent bullets and cartridges.