Looking for a 42 point miranda to fly alongside super Dash... TLT and bomblet generator are pretty much guaranteed but that leaves 4 points left. Chewbacca crew? Harpoon? Cluster mine? What do you guys think?

Harpoon missile, or Sabine or C-3PO Crew.

Like @jwilliamson12 said, I figure you can go a few different ways with those 4 points...

1. Sabine makes your bomblets much more effective. With her on board, the bombs become less of a movement deterrent than a main offensive weapon unto themselves. With the last 2 points, you can add a minor torp/missile, like Seismic or Scrambler, throw some Vectored Thrusters on there for surprise maneuverability, or go with Advanced Slam for an extra action if you need to get the H-E-Double-Hockey-Sticks out of Dodge.
2. C-3PO gives you a lot more survivability, making it a lot more likely to get that evade result when you really need it. He only leaves you with 1 more point, leaving only S-Thread Tracers as a viable upgrade option (which seems silly).
3. Harpoons are just plain nasty, and with Miranda's ability, can become utterly terrifying when used against the right target. A Locked/Focused Miranda will get 4-5 damage results almost 90% the time (4 dice missile + miranda shield boost).
4. Don't forget freebie options, too, like Long-Range Scanners or Guidance Chips, either of which makes ordnance more feasible, or crew slots like Chopper or Courier Droid. The likelyhood of using them may be low, but situations may arise when you want to force/dictate the engagement areas, by deploying Miranda first.

I've only ever landed a handful of bomb drops with Bomblett Miranda so I eventually dropped Sabine.

I would also recommend C-3PO crew and Long Range Scanners.

I tend to focus when I'm in the furball so grabbing that target lock before engageing is nice.

With C-3PO and Mirandas ability you can almost guarantee 2 damage mitigation per turn which is huge in a 1 on 1 endgame.

Im my Rey and Miranda list I eventually put Engine Upgrade on Rey(62pts!?!) and had a 38pt Miranda with TLT, Bomblett, Chopper Crew, and Long Range Scanners.

Baseline is TLT and Bomblets. The adds:

Harpoon Missile or Vectored Thrusters with 2 points of crew (Sabine, Rey, and Jan Ors all have their merits).

Even a plain Harpoon with either just Guidance Chips, or LRS and Focus/TL can do a lot of damage. It's a 5-dice attack presuming you spend a shield (you should). That can make a pretty good dent in something, particularly if you're also hitting the target with 4 dice from Dash. He's unlikely to proc the Harpooned! condition, but throwing a lot of hits at something is always good.

Alternately:

Vectored Thrusters is something I think folks have slept on for Miranda. Getting re-positioning on heris wicked nice. She *can* SLAM, but that shuts off her attacks and her regen. A barrel roll is pretty cheap, can slip arcs, can dodge asteroids, can get range for TLTs (in or out).

Sabine does more Bomb damage. That's great. But some games you won't really do too much Bomblet damage, since you'll be predictable, and many ships move after Miranda these days. Mandalor's answer to Banksy still good, but she's not stapled on Miranda like she was before the Advanced SLAM nerf.

Rey does more turret damage. You can roll up with a stack of tokens and double-focus or focus-target lock to taste (focus-TL primary attacks at R1 are nasty). You might only hit with bomblets twice in a game. You'll shoot your TLTs every round. Having extra focus can easily make attacks hit an extra two or so times over the course of a game. Extra focus for defense is also sometimes useful.

Jan Ors takes less damage. Having an Evade token is handy. You'll be missing out on offensive dice modification. It's also possible for DASH to Evade. If you're running Kyle Katarn, having Focus/TL/Evade on Dash is wicked nice.

I would agree with either 3PO or Rey. Rey provides INSANE versatility, and room for Adv. SLAM or VT, which are great, as mentioned above. 3PO just makes her that much harder to kill, which on Miranda, is dope.