This is an aftermarket gasket, and I haven't heard the brand before.
It said 86 - 03 so it should fit but be aware that some holes could be off a bit and you may need to modify it.

rotella T 15-40 is good enough.  you'll find it at wall mart

when you look up the gasket there's an option for a K&N filter, good enough.

SUZUKI 1995-2009 LS 650 P SAVAGE EXHAUST PIPE HEADER GASKET 14181-45C00 SM-705-1

welcome neighbor

I had my header off at least twice, never replaced my gasket.
Just be gentle and expand it a little.. Clean up where it sits..

Have a place to set the tank down prepared that protects your speedo cable from being bent hard.

A piece of cardboard with the general outline of the clutch cover with a slot in it for each bolt. Avoid creating a puzzle.

Now is a good time to inspect connectors, general whole bike inspection, spokes, wiring, bolts, yadda yadda, etcetera and all that.

You're gonna be wishing for a pretty nice little set of clip pliers.
Look at Verslagens posts, the picture at the bottom shows what you will be up against.

I always start with a clean floor, makes finding little things easier.
A good quality 1/4" ratchet, and a gentle hand. It's a lot easier to snug it up if it leaks than repair a stripped out hole.