According to Ross Seyfried, in Rifle Magazine, LBT will make you a custom mold in any caliber and bullet weight you want (within reason). So if you want an LFN .458 450 gr. mold, that's what you order. Or a WFN, or whatever.
Ross said you should buy and READ their catalog - about $5 - as the information in it is priceless whether you buy anything or not. And, I imagine, it will tell how to order your mold.
I don't cast bullets, but I remember reading the article a couple of months ago. Good luck.