Fun to think of plug-ins one could do, had one time enough for the worlds...
James Blish, Cities in Flight . Great place for trading and non-combat scenarios, but upgrading would be a little strange ("I've got Yuma, Arizona. Can I trade up to Baltimore?").
E.E. "Doc" Smith, the "Lenseman" books. Fun language (Zwilniks, Boskone), and weapons (the Negasphere, the Sun Beam). Inertia-less drives don't really work, tho.
C.J. Cherryh, the "Chanur" stories. Translates almost perfectly to EVO, with brave merchant ships, Station politics, strange aliens, and a war brewing that a single captain can influence the course of...
Charles Sheffield, Godspeed. A fun premise to try to incorporate; over-use of jump drive has collapsed subspace, restricting humanity to a single multi-planet system. Until now...
James White, the "Sector General" stories. I don't know how you could do it, but wouldn't it be fun?
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WIth Herb Caen gone, someone gotta use up all those ellipsis...
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"Ame" Arashi