I'd personally recommend spending the money for a good throttle servo. Don't skimp just because it "might" be OK. I like your original choice for servos. Hitec 7955 is the toughest servo on the block. The 7954's are based on the 7955(basically the same, just with steel gears in place of titanium/helps cut a bit of costs, but should still be plenty strong). Plus this way you don't need a regulator for your lipo receiver battery. If you run a lower end Hitec servo, you will need a regulator, and now you could have just had the better servo for the same $$$. I say stick with the 7954's or 7955's. Don't waste your time with cheap servos. You WILL spend more in the end.
That Orion engine is a pretty good one, but for the little extra $$ I would just go with the Werks B5. They're both sirio based, but the werks is a 5 port, has the new 2010 carb, and has awesome support on here from the owner of Werks(Ron). Check out the Werks B5 thread in this section and you will see what I mean. No extra connecting rods needed.
