While I might have the detailed response that willb gave, I usually like my Macedonians to have their sarissas about three-four times the height of the miniature as that gives a good impression of the length of the weapon without being too long for the table.
Thinking of the table, I would have to encourage Wargames Factory to avoid level pikes because, while they look nice for display purposes, they are a pain in the rear on a wargaming table: pushing into enemy ranks, hard to line up Macedonian ranks, etc. I have had fits with my 1/72 Zvezda pikes trying to get their leveled front ranks to intermesh their pikes and resorted to mounting them on multi-element bases of two ranks of four.
Would be much easier and still visually satisfying to have pikes at 45-degrees for front ranks then held upright for rear/marching ranks.
Just my $0.05