I've owned both the MC 275 MKV and the MA2275. They do not sound the same. The MC 275MKV is superior. Suggest you bite the bullet, do it right the first time and just buy another MC 275. I paired it with an Aesthetix Calypso with NOS tubes... a very nice pairing and highly recommended.
As far as KT88's, I used both the stock tubes and Golden Lion re-issues. I preferred the Gold Lion's, but the stock chinese KT88's sounded good too. I think the main focus should be on rolling NOS signal tubes. I used both Mullard CV4004's & Telefunken's in the 12AX7 slot & Sylvania gold label 12AT7's.
As far as KT88's, I used both the stock tubes and Golden Lion re-issues. I preferred the Gold Lion's, but the stock chinese KT88's sounded good too. I think the main focus should be on rolling NOS signal tubes. I used both Mullard CV4004's & Telefunken's in the 12AX7 slot & Sylvania gold label 12AT7's.