Pre-1988 (or slightly later, depending on the model) Hondas just aren't as common in comparison to the later model cars. On top of the lower ownership numbers, fewer people want to modify those cars (or otherwise learn about them it seems).
I know what you mean though. I just picked up an '88 Prelude 4WS to daily drive and restore. Besides some better brakes, better tires and an iPod hook up, I really don't want to change anything. I just want to clean it up and get everything working fine.
Yet information seems difficult to find.
All the emphasis is on '92-'01 Preludes (4th and 5th gens). And they're just not at all similar to the 3rd gen I'm driving. Not even the same engine series.