Remove, blast and power coat.
It is quite a big job, but doable in the driveway. There are 2 sub-frames, only the front one has the VIN.
Whilst there, think about clutch replacement and engine front cover. I did mine a few yaar ago at around 130,000 miles. Once finished i had to clean up the VIN number to make it legible, the powder coating had completely obsucured it.
I also had the engine and gearbox cases powder coated. Because it was apart I installed new pistons, rings, bearing shells, camchains, chain guides, engine roller bearings, gearbox roller bearings, all shaft seals etc.
I also had the body panels done to match the new frame colour - beware it can become addictive:
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