Firearm reamers are a very specialized tool- the items on ebay that are not specifically listed as being for a firearm are probably unsuited for that purpose. The link below is to a company called Brownells that is a very large mail order supplier of parts and tools to the gunsmithing trade.
CLICK HERE: Gunsmith Tools & Supplies on Sale - Brownells
Please go to their tab on ordering, and then the tab on international sales. There are a number of items that cannot be exported from the US without an export permit issued by the US State Department. Those items include items you would expect to be on a restricted list, such as firearm frames, barrels, etc- but include items you might NOT expect, such as certain telescopes.
Your English is MUCH better than my Spanish, but some technical terms do not translate well. If there is ever confusion over a term any of us may use, please speak out.
SOME of us are still trying to learn English!
Many gunsmiths purchase barrels that are already bored to a given diameter and rifled, and cut their own chamber, mounting threads, muzzle crown, etc. I regret that I cannot offer more advice- I am a hobbyist, not a gunsmith, and have never attempted to rifle a barrel other than building a muzzleloading black powder rifle, and recreating the old ways of cutting rifling.