Trixter - I think SH makes those engines. They're sold as Dynamite, Sportwerks, and Losi. I used to run them as practice engines for 1/8th scale and there are quite a few people around here who race with them in the truggy class.
Any engine that can get an LST moving that fast, is putting down the power! Haha. They tune well and hold up excellently for a sport motor. I think it'll be a great fit for the 8T and RTR.
Jake - It's important that the servo horn is the same length as the bellcrank it hooks up to. Otherwise, you'll have mechanical exponential. As long as you can maintain that geometry, trimming it should be fine. Otherwise, like "cornerspeed" said, Losi makes an aluminum servo arm that will work perfectly.
And for what it's worth, I've been using the stock plastic one.
icemandolmite - I've been running the truck as it comes out of the box. The stock setup works good! Haha. I don't think any of the team guys have strayed too far from it, either. If you want to try something a little different, try Truhe's setup from the Losi website.
trixter - The 8T RTR is listed as backorder on Horizon's website still, so it's not being sold yet.