RE: Would this work for a truck
I think that 2 good small blocks in a big truck could work great. As someone said, the best of both worlds...good combined torque, and screaming upper end. I'm doing a Titan twin conversion right now, and was actually considering Traxxas 2.5s, but ended up buying Hyper 8 ports. A lot of people are putting monster blocks (XTM 24.7 Pro, Picco .26, etc) which doesn't make a lot of sense... The truck will already have wheel-standing power with almost any .21...
I guess it depends what your goal is...twin Sirio .27s would certainly add the bling factor for a show truck, but wouldn't be practical for normal use.