welcome back into the mix!
A LOT has changed over the past 15 years... while you can more than likely fit modern electronics in your dated cars, I probably wouldn't rely on them lasting very long without experiencing some broken parts and your biggest struggle will more than likely finding spares
That said, I wouldn't hesitate to drop in new equipment and run some practice laps just to knock the rust off your boots, but I would encourage you to consider buying a new kit in the near future if you want to be competitive.
Are you planning to get into stock racing or will you be running open mod?
As far as motors go, I'm partial to the Trinity Monster Max, but the Tekin Spec-R series are pretty strong too.
HobbyWing is my go to for ESC's
ProMatch Racing for my LiPo's
If you decide to buy a new kit, then I would narrow your choices between Tekno, XRay, Schumacher or Yokomo... I currently run Schumacher K2 but recently picked up a Tekno EB410.