My 73 F350 came to me with a streetmaster on the 460 and I swapped it onto the "new" used engine. Pulls hard down low but it's like someone through the anchor out at 3700. When it's got a load on it's kinda funny how how hard it hits a wall at that RPM. For what it is I don't bother swapping it. It's a 40+ year old dump truck, 3700 and tiny runners ought to be enough most days. Sorry, I don't have any 385 dual planes laying around anymore. DSC had some used ones the shelf last time I needed one.