You should be able to purchase the ally tube from Mc Master Carr.
You may be able to use what you have by rotating the engine mount a few degrees.
Yet another possibility, make a splice in the middle of the header using a custom molded silicone coupler. For glow, you will need fiberglass and Permatex Ultra Copper sealant and an appriately shaped mold from balsa. This approach makes a flexible goose neck and eliminates broken headers.