I'd not consider myself a proper Shadowrun player. I played a bit of 1e, then more 2e, back when they came out while I was in college, but we were AD&D players looking for a change of pace from our regular game. I love the concept of SR - the Awakened World, the cyber, Deckers and Riggers, the gritty feel of the world as developed by FASA over the years. My problem is the system. I've been playing older editions of D&D for a lot of years now (like 30ish) and changing to something so different was never comfortable. We just never got to the point where we felt comfortable or proficient running the game.
So, fast-forward to 2009. In the D&D world, we've been given the Open Gaming License and any number of new retro-clone games have arisen that recreate the simple rulesets of early D&D. Using one of those as the base (Swords & Wizardry White Box), I'm attempting to write a simple ruleset that gives me the feel of SR. I imaging that most of you true SR guys are recoiling in horror now, but there it is.
Some goals:
1) It is D&D derived, so will by default be a class-based system. Hence my need for the core archetypes. That said, the classes will be very loose. Nothing like d20 D&D or d20 Modern. I'm talking original 1974 style loosy-goosy.
2) Magic does need to be rewritten so it is a drain/point-based system, not D&D Vancian style magic. Got to write up Astral Perception/Projection stuff. That rocks.
3) Other things that I think are core: Matrix/decking rules, Rigging, Cybertech and gun rules, vehicles & drones (control & combat). Metahumans being able to play any archetype/class.
4) Ideally, one could pick up the old 1e/2e SR books and adventures for all the fluff and plot hooks but run my rules to play the game. Yes, it's going to be interesting to try to write this.

So now my questions:
1) What do you consider the core archetypes? I need 3-5 base classes that essentially cover any character concept a player would want to run. My initial idea is a "soldier/warrior" class that could be a Street Sam, ex-Merc, Corp Security, Cop, etc. Focus on combat & firearms. A single class for Mage & Shaman. Where you get your spells and what you can summon is just window dressing. How about a single tech class that covers Deckers and Riggers? They jack into different systems for different reasons, but at the simplest could they be one class? More like SR4, I guess, but would focus on one aspect or the other, not be able to do both. Phys Ads - a separate class, I think. What else? A Fixer/Info guy with contacts, street knowledge & info-gathering skills?
2) To take this all a step further - what else overall is core to the SR feel or experience?
I realize that the members of this forum, especially, are not the target group for my project, but I hope I can pick your brains to be sure I get everything I should have packed into this baby.
Thanks in advance!