I've had success with 8-speed Ergo levers and a same era ('97, I believe) Racing T RD shifting 8-speed Shimano or SRAM cassettes that have been respaced to 5.0mm. I use the Wheels Mfg kit for this, but Shimano 7-spd spacers probably work fine, too, for less money. This conversion does benefit from the slightly longer lock ring that Wheel Mfg supplies in their kit.

Big benefits are much greater cog range, price and availability from Shimano/SRAM. It also seems like the Shimano cogs last longer. I mix cogs to get the tooth counts where I want them, regardless of "group" with no detriment in shifting quality.