Honestly, I think the Epstein Drive from The Expanse would do the job, for you.
Beware! All of the links include at least some spoilers about the TV show and the novel series!
Youtuber Scott Manley (who has a degree in Astronomy) provides an overview, here:
https://www.youtube.com/watch?v=SIaGXcEnC74
He goes a bit more into the mathematics of the Epstein Drive, here:
https://www.youtube.com/watch?v=JWZqp0QoXcw
Winchell Chung over at Atomic Rockets also looks at some of the other aspects of the show (which he obviously loves):
http://www.projectrho.com/public_htm...s--The_Expanse
I have to agree with previous advice that says to figure out what you want to accomplish, with your setting, and then build your technology to fulfill that goal.
The Epstein Drive turns every ship -- and its cargo -- into amazing WMDs. With something like that, a ship just needs some mass-drivers to put dumb cannon-balls -- or even shotgun pellets -- on needed trajectories, because the energy they have at those velocities will vaporize anything they hit.
If you want smart missiles and
lazors and stuff, then you need to a reason those expensive systems work better than simple guns firing dense pellets.
For that, you need to slow down the ship's actual velocity, while keeping Solar System travel times to days or weeks, instead of months or years.
A pseudo-velocity drive, such as the "blink-warp" (a version of 2300AD's "stutter-warp" drive rendered in GURPS rules) or something would do the trick for you.
The discussion re-emerges periodically, so here's a link to the thread on these boards where I first went into it. It's post #35.
http://forums.sjgames.com/showthread...n+stars&page=4
Basically, forbid the FTL threshold and just say that, once a ship gets far enough out of a gravity well, the stutter-warp allows for the useful pseudo-velocity to allow it to travel around the system.
Inside the well, it has to use more traditional (and realistic) maneuver drives of whatever type best fits your setting.