Kind of off the wall long shot. FPA makes 57 car headers for FE’s and 429. Some limitations. He also makes the 4 tubes for the birds, of which I have a set. At least at one point, J Mummert was selling those. If there was a market, between the 2 of them there might be a possibility. FPA is a real quality product, and his bird units did well on Ted’s dyno mule.
There would also be the possibility of ordering the FE’s uncoated and modifying them. I can’t speak to the tube sizes or lengths being applicable for a Y block, and the flanges would have to be replaced. Stan’s in Auburn used to make the y block flanges, but they retired and closed up shop. It may be an employee got those patterns and is still around. He was 8 miles from me and I might be able to track someone down. They’re a shorter design, but longer than the other current options I’ve seen.
Oldmics2, you the gentleman I sold the Don A parts to a while back?