Well, that toy is based off of G1.5 Skyquake. And Funpub used Energon Starscream for Skyquake. So you could use that as a base I suppose. Classics Prowl would be a great head for it if you go Deluxe and use E-Screamer as the base or Deluxe Cybertron Starscream.
Personally I'd go for the huge Cybertron Leader class Starscream as a base. It'll have the right imposing size and as a Starscream already it'll have the right design to the body and jet.
As for the head? I've always thought that the head looked a bit like G1 Prowl. So if you can find a Prowl head (G1 style) that fits I'd use that. I'm not sure how big the head of the Starscream's head I suggested is but if Alternator Prowl's head fits it, I'd use that. And then use a dremel and epoxy to make the mouthplate.
http://www.tfu.info/2005/Decepticon/Sta ... scream.htm - Cybertron Leaderclass Starscream (I qualify because there's a Deluxe sized Cybertron Starscream)
http://www.tfu.info/2005/Autobot/AltProwl/prowl.htmhttp://www.tfu.info/2005/Decepticon/TRU ... scream.htm - Cyb Deluxe Starscream.
Now that I've checked out Cyb Starscream's head it might work, but you'd need to sculpt on the horns and a faceplate.
Also if you're feeling up to making more than one if it turns out you should do the same custom in Skyquake's colors:
http://www.tfu.info/1992/Decepticon/Sky ... yquake.htm