Depends on the engine mount you have or if you want to move the trans forward 1/4" or so. A big block clutch won't fit without moving the trans forward as you also need to get a BB bell so the shoes have enough surface to contact with. The BB mounts usually are cut so the stock...
I think I'm running the alloy set on my BB revo at the moment and the teflon set on my SB revo. Got tired of slippage on the BB revo. Come to find out... it's running slayer gears in the trans. Explains so much as to why I keep seeing guys with BB's running much taller gearing than me. That...
Can't say for sure as I'm not sure if those shoes/springs are for 1/10 or 1/8 sized flywheel/bell. Since you said 27 Sirio (haven't heard that name in many years), I'm assuming your looking for a 1/8 scale setup.
You can usually find decent RTR shoes/flywheels on ebay all together for pretty...