Ca_Tony. Sounds like a lot of work. I am sure in the end
it will be worth it and you will be proud of your project
bike....but....
Maybe you should just buy a GG SM already made.
There is a guy over in SuperMotoJunkie that has
been trying to sell his for some time now.
http://www.supermotojunkie.com/showthread.php?t=62630
You may have to join the group to get the link to work.
or search there for "2003 Gas Gas 450 SM/Ohlins"
If you are firm on sticking with a pre-2005 FSE motor.
Do some research as the earlier motors are know to have
some problems.
A friend of mines 2003 swallowed a valve and after a small
truck load of $$ replacing just about everything from the
base gasket up. ~50 miles later it tossed the rod through
the cases and grenaded the motor. In GasGas USA's defense.
They replaced his bike with a new 2005 for all his trouble.
Try getting Honda to do that!
If you do choose to continue with your project. Please keep
us up to date as you are developing some possibly usefull
information for the whole GasGas community.
Best wishes on your project.
Jeff