Injection pump upper gasket

[NickIX]

I've tried searching but wasn't able to find anything that was related to my issue. I've rebuilt a couple of injection pumps over the years and have always used the Bosch 121 kit. The problem with it is that the top gasket doesn't fit and I have to trim it down to fit in the housing. Does anyone know of an alternative gasket for our ve pumps upper housing?