I don't think so.  The System/360 letters referred specifically to the amount of memory available, so a D compiler would run on a D machine with 256K, and E/F/G were 512K/1M/2M.

The DEC floats were an extension of Fortran's exponent letters:  D=double, E=generic, F=single.  G is a variant of F with a different mantissa/exponent balance, and H is double double.   S and T floats came later and were bit-for-bit compatible with IEEE binary32 and binary64 formats.  Lisp went a different way: to D, E, F they added S for small floats and L for large floats.