Author of 'Hellfire', 'Riders of the Storm', 'House of Pain' (sequel to House of Hell) and 'Deathtrap' (prequel to Deathtrap Dungeon). All are available for download here or at: www.ffproject.com/download.htm
Anyone ever counted that? Or how many words per section?
On the assumption that a quick and dirty estimate is probably of some interest to get things started:
The Port of Peril (which I have to hand) has 266 pages if the Background but not the Rules is included. A randomly picked page has 53 words across the first five lines, so it averages just under 11 words per line. The same page has 20 actual lines on it.
266 x 20 x 11 = 58,520 words.
If that method is not completely unsound it's probably accurate to within 5% either way. Whether that's typical of FF books or even Ian Livingstone books I don't know, but it wouldn't take you a vast amount of time to find out.
Edit: FWIW my 167 section mini Murderous Mire is roughly 21,800 words long if you include the spells.
It's all very subjective. Is your narrative detailed enough? It could be sparse or detailed and still fit the bill. Maybe if you are unsure yourself have a few people read some paragraphs and comment after. Word count is meaningless, unless your under some sort of contract/budget where you've been ask not to go over a certain size.