Sorry about that. Originally tried your "name-ext.zip" preference and left the baggage to trip over itself.
Code:
for /R %%i in (*.txt) do if %%~zi GTR 250000000 7za a dummy -tgzip -so %%i > %%i.gz && 7za t %%i.gz && if %ERRORLEVEL% EQU 0 erase %%i
BTW, if you look at help for these things it's all self explanatory. At least you'd recognize what's going on. Stringing it together is just a matter of familiarity.
This old DOS stuff isn't something to be impressed by. Go for PERL or other if you have real work to do. It'll mean fewer migraines.
