Can a CZ 550 in 458 win be converted to a 458 lott is it an easy fix or do i need another action length

The 550 is chambered in both the 458 and the Lott. I think I've seen more in Lott than 458. Should be an easy change.

are they the same size action

Yes "MIGHT" have a different follower and or mag box

Triple River Gunsmithing rechambered mine. No big deal. No new parts.

i think i will talk to them ty