[Masquerade]

Piggybacking off the advice given by Cesar,

You can merge both your srep and srep64 methods into one packcmd providing the exes are in the same folder as arc.exe:

Code:

[External compressor:srep, srep64]
header = 0
packcmd   = {compressor} -a1 -m5f $$arcdatafile$$.tmp $$arcpackedfile$$.tmp
unpackcmd = {compressor} -d $$arcpackedfile$$.tmp $$arcdatafile$$.tmp

Here, {compressor} constant holds the name of the compressor used, e.g. -msrep64 will give {compressor} the value of srep64.

Since FreeArc will look for .exe files by default, filling {compressor} with srep64 will have freearc look and successfully detect srep64.exe.