Moto Grand Prix
Main Motorcycle: '03 Sprint ST
Join Date: May 2004
Location: Baja 'Bama (Panama City, FL)
Other Motorcycle: 2000 Sprint ST (wrecked)
Extra Motorcycle: 1988 FXR Lowrider (sold)
HH, the front isn't really all that bad for your weight, but the seals get rather sticky. As in, "stiction'. The spring rate is about right, but the stiction may make sag determination a drag (pun intended).
The common 'cheap fix' for the front is to drain and clean the tubes, then replace the fork oil with a slightly higher viscosity (numbers are different, depending which side of the pond you are), and installing new seals. Check the bushings for wear while you've got the legs disassembled.
The dust caps are probably fine; you'll want to use NOK seals (which are OEM fitted).
A quick way to 'test' for the stiction is to spray a bit of lubricant on the sliders just above the dust caps, jounce the front a couple times, then take the bike out for a quick spin. If the front feels 'smoother' you might have an easy fix in front of you.
Now, the rear shock wasn't great when it was new, and yours is 12 years old. The Showa unit is rebuildable, probably for a lot less money than an aftermarket unit will cost. There are several threads on that subject.
'Tmod' is our forum suspension guru; search for his threads.
One last tip: Disassemble, clean and lubricate the fork stem bearings while you're at it.
Oh, and be very careful with the speedometer pickup when you put the front wheel back on. It is easy to mess that up, and ruin the pickup.