Can you get hold of Mgd 4 FB ? This is a neutral paper, and it stays neutral after selenium toning.
Another suggestion: Have you tried Dektol at 1:9? When I used this with Mgd 4 FB it came out blue black - cooler than at 1:3. Don't know if it works like this with Mgd warmtone but it would be worth a try since you have the paper and the developer.