We're going to turn the original post upside down, cut off the bevel and cut a notch in it for clamping. Then we'll fit a clamp and assemble it all.
You'll need :
? Seat post clamp to fit a 1 1/8" tube
? 25.0mm seatpost
If you use a Twenty clamp, you'll have to shim it down to 1 1/8".
For tools, you'll need:
? a hacksaw
? 3/16" bit
? center punch
? round file
? flat file
? tool to tighten the new clamp as required.