[@Unfortunately]I just got a better idea:
[url]http://www.projectrho.com/public_html/rocket/enginelist.php[/url]
Pick whichever engine designs you would like the most for this RP.
There's actually quite a difference between even two nuclear torch engine designs. Some may even feel insane yet strangely practical.
Orion drive which basically lets the ship ride on a series of nuclear explosions; for example.