stuffit,
My advice is to NOT try and rebarrel your SMLE jungle carbine unless you have the proper barrel vise blocks (aluminum, not lead) and the proper fitting action wrench and blocks. To do otherwise is asking for receiver damage and frustration. The SMLE surplus barrel may or may not index correctly to your receiver, and if it does not, you will need a lathe and headspace gages to install properly.
The mechanics of rebarreling are not rocket science, but I've seen many military surplus and commercial arms ruined by shadetree mechanics that did not have the proper tools or knowledge for this.
A gunsmith will probably charge you $40-$60 for a simple barrel swap if no fitting is required.