I heard that maybe the backplate of the engine might need to be checked so that the screws are screwed in with locktite. Some 25 engines were okay but I heard some were loose. I know this was a big problem for the RTR but not so much with the SS kit versions. In any case, you might just want to double check it since everything is out anyway. I bought an SS kit and it wasn't tightened right.
The SS kit is really fun to put together. Majority of all the parts fight really well and the instructions are very clear and easy to understand. The transmission and differentials are already preassembled, so that's a big plus (at least for me).
If you're thinking about enabling your Savage to move reverse, NOW is the time to pick up that reverse module ($35) and pop it in. The Savage SS (and the RTR) is VERY durable and tough. I've crashed it really hard countless number of times and the truck just keeps on ticking and keeps going strong. Hard plastic, good handling for a truck, and it'll keep you happy on the speed side.
I think the only thing that you might want to watch out for is that make your measurements carefully and as precise as you can when it comes to the suspension alignment affected parts. I just eyeballed it and did whatever. And after I finished putting the truck together, my alignment was completely off and I had to use my setup alignment station to correct it. (it's a pain)
But other than that, good luck on building it...you'll have a lot of fun with the truck!