Here's some random quotes just off of a Google search:

"And Ready To Die's most omnipresent hit “Big Poppa” flaunts the West Coast's signature Moog keyboard sound." - https://www.vibe.com/2014/09/unpopular-opinion-biggies-ready-die-hip-hops-most-flawed-classic-album/

"In light of the imminent coastal feud, it’s strange to consider how influential the West Coast was on Ready to Die. Snoop’s nasal twang and Dre’s pistols and palm trees epiphanies supply two of the album’s first samples. East Coast producers had been heavily mining Ohio funk since at least EPMD, but the hydraulic groove and the laid back pockets of “Things Done Changed,” “Juicy” and “Big Poppa,” are indebted to what was bumping out of Death Row. The “fuck everything sacred” slant almost invariably came from Ice Cube and N.W.A." - http://www.vinylmeplease.com/magazine/ready-die-liner-notes/

"“Big Poppa” was inseparable from Ron Isley's “Between the Sheets” and snuck in a trendy, post-regional synth line that would perk up West Coast ears." - https://pitchfork.com/reviews/albums/22952-ready-to-die/

"For every swaggering corner boy anthem (“Juicy”, “Who Shot Ya”, g-funk-jacking slow jam “Big Poppa”) there's a corresponding blast of hood paranoia and introspection (“Warning”, “Suicidal Thoughts”)." - https://itunes.apple.com/nz/album/ready-to-die-the-remaster/id204669326

"When you were listening to it, that was his success, because he took like west coast sound." - http://www.makaveli-board.net/showthread.php?12672-How-big-of-an-influence-was-2pac-on-Biggie-s-ready-to-die-album

These are basically all from established sources, too...I was in L.A., but in 4th and 5th grade, I didn't pay any attention to Regionalism at all, so I never even thought about it. But it's a lot of folks who have mentioned that his 2-3 singles had a G-Funk/West Coast inspired feel to them.