my experience with shim kits is you get too many that you will never need. the valves almost always get tighter over time, not looser. no harm in sanding them down for a fit, they are through hardened high alloy steel
before I got a surface plate I used a piece of glass. tape the sandpaper to the glass, hot glue the shim to a piece of dowel
if I'm answering your question I assume the basic points have been addressed, such as: did you do a compression test? is it still on fire?
Last edited by Beezerboy; 01-13-2017 at 03:17 AM.