Well, I don't know about Scheckter, Wes.
F5000
June 7, 1970
Ron Grable Lola T-190 1:15.7
May 23, 1971
David Hobbs McLaren M10B 1:14.9
Sept. 30, 1973
Brian Redman Lola T-330 1:14.3
And 1973 was the end of that.
In the shall we say 'current era' and track conditions I believe the lap record holders at Seattle today are....
May 27, 2007
Mark Jaremko Stohr DSR 1:17.4
May 25, 2003
Rennie Clayton Ralt RT-41 1:18.3
As a ref. BLAST ground pounder... Mike Rocket 1:21.8
Don't know what Randy's lap times are.
As an aside:
Jaremko may also hold the FF lap record at 1:27.2 in a Stohr beating Ralph Hill by 0.3 seconds in his DB1