You could take the Shimano cassette off your current wheel and put it on the Reynolds wheel. All it takes is 30 seconds with a chain whip and lockring tool. The 11-26 is missing the 16t cog that the 12-25 has. The 15t-17t jump can be annoying.

The Reynolds blue pads are the best for Reynolds carbon wheels. Using anything else will void the warranty. If you use the carbon pads on aluminium wheels you must remove them and pick out the aluminium shards before using them on the carbon wheels. All this is on Reynolds web site.

Reynolds pads cost $30 pretty much everywhere. No need to buy from the UK.