I use a spreadsheet too. Saves head scratching. Correction. Saves some head scratching. “Some” because you will measure things as accurately as you can, put in what should be the right shims according to the simple math, reinstall the cams etc., remeasure the gaps and, as David says above, find some are still not bang on. It’s why having access to a box of community shims, per Michael’s point, is so helpful.
Here’s a screenshot of the spreadsheet I put together years ago - still works:
I posted a link to it (the file extension to which needs to be changed to .xls before it will work to satisfy the security provisions of the J-L site software) here: