UPS flat rate saves a sale

UPS has a flat rate now, "UPS simple rate", A little less structured than USPS flat rate. they have 4 sizes determined by the box volume. If your box is under 1720 in^3, and under 50#, your good to go for "extra large", $23 in CONUS. I just shipped a pair of 273 manifolds from CA to PA for $23! Now you might be able to ship bare iron heads for <$50 a pair in 2 boxes if you can get them under 50 lbs each, IIRC B/RB heads are lighter than LA heads.
Flat Rate Shipping from UPS® | UPS - United States