Those were more than Yellow fork legs, they were trick Simons forks.
Here is a link to a Cycle News article about Marty's LOP bike. It actually displaced 493cc!
I'm a 465 owner too, mines an H model 1981. Bought it new, back in the day, influenced by Marty's win
and all of the magazine raves no doubt!
In 1983 I was stationed at Great Lakes IL (Navy) I met a few of the LOP gang, including Craig Anderson
one of the guys that built Marty's bike. Never met Laurens Offner, but the guys at the Suzuki shop I hung
out at, shared many tales of the exploits at LOP!
Here's my bike in '82 at Carlsbad.