I've switched out take-offs and not had an issue w/ headspace.
I've switched about 7 -8 of them. All but one headspaced just fine..
Man, I must be the most unlucky smith in the biz...
In the dozens or so that I've switched out only ONE that I can recall had headspace within SAAMI range and that was about a year ago.. That one also aligned just right too...and that was a M70 classic barrel.
Every now and then a blind squirrel finds an acorn..