Need some help with Luarocks please

I finally bit the bullet and thought I would try Luarocks, it was as I anticipated a painful and unpleasant experience. I would appreciate some help please

My setup

Windows 7. I have been using LuaForWindows previously without problems. I am targetting Lua 5.1 for my work.

I have several Visual Studios on my PC so want to use VS for the compilations.

Luarocks Installation details

Will configure LuaRocks with the following paths:
LuaRocks        : C:\Program Files (x86)\LuaRocks
Config file     : C:\Program Files (x86)\LuaRocks\config-5.1.lua
Rocktree        : C:\Program Files (x86)\Lua\5.1\\systree

Lua interpreter : C:\Program Files (x86)\Lua\5.1\\lua.exe
    binaries    : C:\Program Files (x86)\Lua\5.1\
    libraries   : C:\Program Files (x86)\Lua\5.1\
    includes    : C:\Program Files (x86)\Lua\5.1\include\
    architecture: x86
    binary link : lua5.1.dll with runtime MSVCR80.dll

Compiler        : Microsoft, using; call "C:\Program Files (x86)\Microsoft Visual Studio 8\VC\vcvarsall.bat"

Luarocks Errors

I tried with LFS

luarocks install luafilesystem

Setting environment for using Microsoft Visual Studio 2005 x86 tools.
Installing https://luarocks.org/luafilesystem-1.6.3-1.src.rock...
Using https://luarocks.org/luafilesystem-1.6.3-1.src.rock... switching to 'build' mode
cl /nologo /MD /O2 -c -Fosrc/lfs.obj -IC:/Program Files (x86)/Lua/5.1/include/ src/lfs.c lfs.c
link -dll -def:lfs.def -out:lfs.dll C:/Program Files (x86)/Lua/5.1/lua5.1.dll src/lfs.obj
Microsoft (R) Incremental Linker Version 8.00.50727.762
Copyright (C) Microsoft Corporation. All rights reserved.

C:\Program Files (x86)\Lua\5.1\lua5.1.dll : fatal error LNK1107: invalid or corrupt file: cannot read at 0x2B8

Error: Build error: Failed compiling module lfs.dll

I am guessing there is some compiler version compatibility problem somewhere but no idea where. It is using VS 2005 to build stuff so I thought that should be OK and match the lua5.1.dll and MSVCR80.dll that LuaForWindows would have installed in the past.

As an experiment I thought I would swap the Luarocks config to point at my most recent VS2013 compiler, but I couldnt figure out how I do that within Luarocks.

Does anyone know what config file and line I need to change to switch compilers ?

Any ideas on what I need to do to fix this would be appreciated. Thanks

P.S.

Quoting the official Githb page for Installing on Windows

Installing over "Lua for Windows"
Need some information on this too....

That isnt exactly helpful for us Luarocks newbs ! Would be good to fix that. hint hint !

Regards Geoff

Geoff