That's a tough decision given how far you've come. You are pretty much resigned to a single rear shock (unless you re-weld the OEM tail end back on). However, here is some guidance I saved from the KZ Twins site concerning the OEM front end that might be easier for you to accomplish:
"Stock fork oil is 10W IIRC, due to wear I'd suggest using 15W if you do not want to mod the damper rods.
It's been a while since I messed with the Z400G, I think I did the fork mods in 2005. But I searched around a bit on this site and found this that I wrote years ago:
If you just want a harsh front end for control, you should use 20W or 25W fork oil together with springs from Progressive. However, if you want a compliant, yet controlled ride with reserves for big bumps, here's my recommendation:
Drill out the lower fork damper holes to 1/4 in to reduce compression damping. Clean everything inside the fork and deburr your holes. Put fork back together.
Fill up with 184 cc of fork oil with 20W or 25W viscosity, preferably synthetic if you can get it. Pump the fork repeatedly to get all air out of the system and the level correct - if you do not pump the legs (do this without springs) your oil level will be wrong. Volume [measurement] isn't accurate enough IMO.
You should remove the springs and collapse the fork completely. Oil level should be 435 mm from the top (17.1 in) - stock. I would start with 410 mm and fine tune from there. Remember to pump the fork repeatedly before measuring level as it will drop a lot if you just fill and measure without pumping."
"Stock fork oil is 10W IIRC, due to wear I'd suggest using 15W if you do not want to mod the damper rods.
It's been a while since I messed with the Z400G, I think I did the fork mods in 2005. But I searched around a bit on this site and found this that I wrote years ago:
If you just want a harsh front end for control, you should use 20W or 25W fork oil together with springs from Progressive. However, if you want a compliant, yet controlled ride with reserves for big bumps, here's my recommendation:
Drill out the lower fork damper holes to 1/4 in to reduce compression damping. Clean everything inside the fork and deburr your holes. Put fork back together.
Fill up with 184 cc of fork oil with 20W or 25W viscosity, preferably synthetic if you can get it. Pump the fork repeatedly to get all air out of the system and the level correct - if you do not pump the legs (do this without springs) your oil level will be wrong. Volume [measurement] isn't accurate enough IMO.
You should remove the springs and collapse the fork completely. Oil level should be 435 mm from the top (17.1 in) - stock. I would start with 410 mm and fine tune from there. Remember to pump the fork repeatedly before measuring level as it will drop a lot if you just fill and measure without pumping."
