I'm running the SH .28 p8 in a pretty heavy solid axle truck, probably heavier than the Savage (it's 11 or 12 lbs). Harnessing the power is an ongoing battle right now. It was a little more manageable with the p3 version.
Yup, the Dynamite .28 is basically the SH28 p3, the Big Red I believe is a 5 port. The .28 p8 is significantly stronger than the .28 p3 (I have both engines). D3MON is spot on with the overall assessment of SH engines - they are very good bang for the buck, and durable.