Sako model 75 in .300 RUM Need Advice on Magazine Extension

[PanBest]

Hello, Mark here. I'm a new contributor but have read the many posts for 15 years or so. I am in need of some advice from the LRH community. I have a Sako model 75 in a .300 RUM. and I need to get a magazine extension for the gun to shoot the .300 RUM longer COAL with the Berger 190 grain VLD Hunting bullets. The gun is 20 some years old and I sent it off to Robar in Arizona to do all the custom work 20 years ago when they were still in business next to McMillan. I need some suggestions of extended actions that would fit that particular model and caliber and qualified gunsmiths to do the work. Thank you so much!!!! I sure do appreciate the advice!!!! PanBest