parameter replacement in make during rule execution

Hi,
I have a makefile which generates a tcl file when a certain target is made:

DO_SIM:
	[many echo commands] >> sim.tcl
	for option in $(OPTIONS); do		\
		echo -n "$(if $(findstring =3D,$$option),$$option,$$option=3D) " >> sim.t=
cl;	\
	done;
	[more echo command] >> sim.tcl

my problem is with the for loop shown. OPTIONS variable has various fields =
in it. Some fields have a '=3D' in them ie. FOO=3D512 and some don't. Becau=
se I have a broken tool which gets confused by variables which don't have a=
n equal sign in them I am trying to go through them and convert "FOO=3D512 =
BAR" into "FOO=3D512 BAR=3D". The trouble is that the findstring never find=
s anything and I get "FOO=3D512=3D BAR=3D". When I replace the whole findst=
ring command with 1, I get the then case of the 'if' but no amount trial ma=
de findstring work. Any ideas what my problem is or how to do what I need d=
ifferently?

Thanks.

By the way, I am running make under cygwin and my make version is 4.0.2 if =
that makes a difference.