"Big Block (BB)" vs "Small Block (SB)" in the RC world generally relates directly to the size of the crank case, not the capacity of the compression chamber.
Take for instance the PiccoMaxx .26 that is made for a t-maxx or revo. It's considered a "mid-block". Big block compression chamber with small block crank case (or close to it).
Generally, BB engines start at .21 and go up. SB engines start at .10 through .18. With the TRX3.3 being a .20 as an exception.
There are quite a few I'd run in a typical savage. If your after more power than the Mach26, the Mach 427 gold head is a good engine for the money. The Mach 427 green/grey head is a hair stronger due to a larger carb and massaged internals.
To step it up a notch, the LRP 28 Spec 3 is a great basher engine. With the right pipe. The picco 28 is even a more refined step up over the LRP28S3 with a bit better mileage and performance.
I currently am running a LRP28S3 in my 1" extended savage and it's on the verge of too much power. With a Losi HT pipe, it really runs well. I run the same engine/pipe on my aftershock and like it for that rig as well.
There are many engines out there and I've only ran a few with the LRP28S3 being the strongest I've owned or seen ran. There are many that are better, stronger and more expensive. There are also many that are cheaper and are good for the money.