If I were going to run Shadowrun I would use Genesys, the system the old Fantasy Flight Star Wars games used. The one with the funky dice.
Shadows of the Beanstalk (The Genesys RPG for Android-Netrunner) provides an excellent rule set for hacking.
A couple of Fan-Made Genesys conversions are out there.
Paul M.N. Haakonsen's Version:
Rob 'Chaithi' Thayer & Surukai's Version:
Of the two, I like Haakonsen the best, as it actually tries to explain stuff, While Chiathi and Surukai are mostly lists of RPG statistics.
There is some criticism of these in the Genesys subreddits that they aren't super well balanced. One recommendation I have read is to just use Shadows of the Beanstalk for Tech/Gear and Hacking, and use Realms of Terrinoth for Magic and Races.
Whenever you do this "Roleplaying game but in another system" thing it seems like there is always a balance. On one hand, you want to let the new RPG system operate the way it was meant to. Obviously you aren't using the native system for a reason, and there is something in this new system that draws you in. But bringing in the new setting often brings with it a lot of baggage, and the more baggage you import, the more stress you put on the new system, until you are just recreating everything you discarded the native system for. I think the two fan versions above do a fair bit of this "baggage handling" so I would use them as resources for your Shadowrun Conversion rather than a wholesale conversion.
