If I could do things all over again, I would purchase a set of 6F8G to 6SN7 adaptors off eBay, and purchase Tung Sol Black Glass Round Plate 6F8Gs. These are the equivalent of the Holy Grail Tung Sol Black Glass Round Plate (BGRP) 6SN7s, which I own. Difference is the adaptor is ~$15 and the 6F8G can be had for ~$180, whereas the 6SN7s are upwards of $300 and usually not NOS, and typically have hairline cracks in their bases, and also, reportedly by many, have a smaller soundstage and image size.
Since discovering that the 6F8G is a 6SN7 equivalent, I have purchased the National Union 6F8G Round Plates, and in my system are the equal of my Sylvania Bad Boy 6SN7s, but not as good as the Tung Sol BGRP. I plan on replacing my current BGRP 6SN7s with 6F8Gs for less than half the cost of 6SN7s when they die.
TLDR: Don't be hesitant to try other electrically equivalent variants, which are cheaper, and potentially better sounding.