I've been doing so for many years. Just don't throw away your first edition rules. For there are some things in them that aren't in the third edition rules. Like (if memory serves) historical notes and a list of what's on the event cards. Mostly some of the "side bar" stuff.
There have been no major rule overhaul on this game would would negate any possibility to use all different rules with the same edition. The changes were mainly aesthetic and I don't recall any real rule change.