What's a 310?
They made 250, 350 & 500 2-strokes, and a 600 4-stroke in 1987.
There had been a 2-stroke 300 in 85/86, but I'm pretty sure they'd dropped it by 87.
But yes, too new for Vinduros ATM. Plenty of events will turn a blind eye to a late 80s bike, but you wouldn't bet the house on it...
If you're in Vic or Qld, then you can race pre-90 VMX on it.
I've got an 89 KTM125GS and a '87 KDX200 that I would love to take to a Vinduro... *sniffs*