Got a emailed returned concerning billet cores for inline 194-250 engines.
"No we do not have any 250 6cyl roller cores. I cant find a listing of anyone who manufactures them."
John Hartman Crower and Isky both have the ability to make their own roller cam billets in-house for the inline 6's and Crower had 18-19 blanks on the shelf the last time I spoke to my rep. People just don't want to pay the price.