@allenf1963 You are welcome. I strongly suggest either Brent Jesse Brent Jesse Recording Supply or Andy Bowman at Vintage Tube Services. Both have fantastic knowledge, test equipment and in the case of Brent a 30 day warranty on nos tubes. He offers precision curve tracer matching for what i consider to be reasonable $. They will both typically have some Mc branded tubes as well.
The 225 and 240 use a very unique output transformer and in the case of the 240 amazing bandwidth and extraordinary low phase shift. Difficult, massive and certainly expensive to manufacture. The 275 is a brute ( in its day ) but imo lacks the 240 finesse. Finally… the 240 i run has been lovingly modified w HK style regulators and a bunch of Russian paper in oil capacitors… photos on my vintage system page
have fun.