Yeah, change the rear brakes to Levin discs. There are surplus ones around 5-6K for the pair including handbrake cable (don't buy if this is not included). Then look for Corona/Exsior brake pads if already needed.

If you put it this way, an AE101 with stock Silvertop can go side-by-side with a stock SiR, and imagine if it were a supercharged GZE or Blacktop! Unless you plan to drag-race hard core, the performance of a stock 20-valve should already be enough for everyday driving.