George's Dagnall clone is attached with the vintage style end bells and therefore will fit in perfectly. And after you've swapped it in, you'll hear, what you've missed tonewise such a log time
Just two days ago I've swapped George's Dagnall clone in a customer's '94 2203, which I've rebuild to a 3-channel-head 10 years ago - and after that I've had problems to avoid, that he doesn't kiss my feet
Do it! Your ears will make eyes!
If your bias was correct before, then rebias the amp isn't needed!
Larry