I'm unaware of anyone making S/S boat headers for the SBC. Maybe, but I bet they're chrome, but as far as blueing, just deal with it! They're gonna blue up to a bit beyond the water injection lines no matter what you do. That's how a trailer queen is discerned from a boat thats used a lot anyway, take it as a badge of honor.
OC2 has a point, they NEED to get off the transom. Fires can start that way! Those fockers get HOT! I thought Moo's engine mounted low, HOLY CRAP!
Looking good though! I'd really be looking into getting that engine up where it needs to be though. At least a little. Else go TT and call it a day......
Ray