It isn't a Toro-Flow. The valve covers on those looked like a 409 valve cover. This one looks like an oversized 6.2L and makes me think it is the 8.2L.
http://www.6066gmcguy.org/toroflow.htm

You would probably be able to get the scoop on the motor.

I like how the injector lines don't go over the rocker covers - I wish they'd have kept that feature on the 6.x.