Leon,
You and I have the same problem but I think we are going about solving it differently. I am putting a 250 in 1956 3105 panel. Rather than using aftermarket cross members, I am using the stock V-8 bellhousing and building my own front mounts. The mounts will fit up to the stock engine mounts that bolt to the engine. I am using a piece of heavy walled pipe and "tophat" bushings on the engine end and 2" square X 1/4" wall tubing that will form a triangle.
If you are dead set on crossmembers, Contact Sachse Rod Shop. They're NE of Garland and shouldn't be over an hour's drive away from you. Page 5 of their catalog shows cross member and mounts that you could use. 1-800-495-3904.
Best wishes,
Les
