One of the worst jobs i can think of on my 32 the Rootleib hood had to be trimmed at the front and metal added at the rear. Not really their fault as they didn't seem to fit that well on standard 32's
I set the grill where i want it and go from there, as the others have said it can take anywhere between 30-60hrs to get it looking right

Here in the UK some builders just space the grill up or down till right, Not my idea of doing the job properly though.