To the gunsmiths out there, is it ok, or a problem relining a barrel that has been relined once before?

If you buy the rifle, I would strongly suggest that you do a chamber cast before deciding to rechamber or buy brass for it.  I have a 40-70 SS that I bought a box of Hornady 405 brass for and shortened it to 2.495.  I was having problems with the primers backing out, a somewhat common occurrence with Hepburns I understand, so I measured the recess depth in the chamber to see how thick a rim was needed.  It was 0.073 and my brass was 0.068 so I ordered some BACO stretch brass with thicker rims to try.  BACO has every combination one can imagine.  I had them send some Cerrosafe with the order and got brave and did a chamber cast which turned out to be super easy.  That's when I found my chamber had been cut for full length 405 brass and everything I had was to short.  I bought a hundred Jamison 405 brass and left it full length.  I then bought a second 40-70 and did a chamber cast right off.  It was the standard 2.5" so the shortened Hornady brass worked great but the BACO had too thick of rim now.  Had I taken the initiative to do a chamber cast right off I would have saved myself heartaches. The other reason to do a chamber cast is to help see the dimension of the throat to help decide what cast bullet to shoot.  Both of my 40-70's have 0.410 throats almost 0.300 long so at least my cast bullets are interchangeable but they have different bore diameters so I have problems trying to use one dual diameter patched bullet for both.  My rifles both shoot as good as I can see with both smokeless and black.  I am not saying they will outshoot a 40-65 but they are both less than 2 moa consistently.  Attached is a target shot with a grease groove bullet at fifty yards with my Hepburn with iron sights.  The 40-70 can be made to shoot!  Tom