Should work, but I'd probably go with 1 o/b dump instead of two, leave the plug alone and run the other through the headers and regulate with a ball or gate valve of the pump.
Trashy headers though, who cares? if they blue they blue. I think you're fine to try it, I just dunno if you;re gonna get enough water pressure to open up the T Valve to the headers.
(I have ruined a perfectly new set of Rewarders on Moo due to water issues on her maiden voyage, and still they remain on there as testament).
Ray