I'm no FI guru, but it sounds right. Get the right fuel pressure to the rail and the stock regulator should send excess fuel back to the tank. The engine should perform as it was in the Astro. The only concern I would have (and it's probably no concern at all) is if the weight or torque requirements for the truck are significantly different than the Astro. Then the computer map may not be right. I really believe that is a non-issue, though.
Good luck with the swap.

Current fleet (subject to change w/o notice)
\'49 GMC 3/4-Ton , 60 Austin Healey Frog-eye Sprite (some assembly required), 2011 Dodge Avenger, 2015 Jeep Cherokee. No, they don't all run.
My other ride is a (B737)no, (B767)no, A320.... Update... was Embraer E190, now Boeing B787.

Knowledge is a wonderful thing, but ignorance means you don't know you can't do something.