Do I have to mod my blaster to use stephan darts?

Oh a Longstrike, I misread Alpha Strike as Alphatrooper. That kit pretty much includes all you need, other than the mags and adapter, though I'm not sure if it contains lubricant, which you also need. I use this stuff, which is pretty good: Could probably also use a stronger boltsled, though I'm not entirely sure if it's necessary, or if anyone even makes any. You could try reinforcing it yourself though if you need to. For magazines, make sure to get the Worker Talon adapter, specifically the one labeled for springers, and use Worker Talon mags in it or Talon-system 3d printed mags such as Thanhlons, and with sealed-breech compatible short darts such as Worker Gen 3s, ACCs, cut down menguns, etc. Alternatively, you could use the larger sized mags that have a short dart follower inside, though those are bulkier and it's more compact to carry Talons (though they have a different aesthetic that you may like). The kit also converts your blaster to direct-plunger, which greatly reduces deadspace and helps increase performance and moddability. As far as I know, it's drop in, and there's instructions available to help get it together, but make sure you at least know how a blaster works and how to disassemble it before attempting the mod.

If I remember correctly, limagicq is one of the Ebay sellers for Nfstrike/Workermod (I've heard it mentioned before, and the banner in the listing's description says "WorkerMod"), which are super sketchy already, and on top of that they're also having trouble shipping out of China due to coronavirus. Outofdarts sells the kit too, domestic shipping in the US is quick and works well (USPS Priority), they ship international too but I don't know how well that is working (depends on your country probably):

Also, someone else who sounds like they used the same kit has a sort of review of it over here:

/r/Nerf Thread Parent