I'm going to replace the chain, and cassett on my Trek 7000 but the chainring has a sticker IG chain ONLY? Can I use a SRAM PC-850 without issue, and is a HG50 the cassette I should look for? The current (original) chain is marked (Shimano IG Narrow). Also, the cassette is a 7spd so I assume the SRAM 8spd chain is the correct choice?

Thanks Capecodder......