[Central-Electronics] Use of Russian 1625s in P&H Electronics LA-400B amp?

[C Eus]

All:
First off, I'm glad to be here and I am looking forward to operating Vintage
SSB using a recently acquired CE 20A.  I also acquired a P&H Electronics
amplifier that uses four modified 1625s.  However, I would like to know if
anyone has attempted to modify the Russian 1625s found at various
suppliers.  Any comments appreciated and thanks. Cal, N6KYR/4