A bigger board isn't gonna make you a better skater, or at least probably not how you think it will.
You say you want to go bigger and faster, well it's not really gonna help you in that respect. I suppose a wider board, paired with wider trucks, will provide a more stable platform if you're doing gaps, but I really doubt a half inch is holding you back from doing gaps.
You're really not a big dude, and I know deck size is preference, but I feel it just makes logical sense that, generally speaking, bigger people ride bigger boards and vice versa.
I'd just suggest maybe an 8 1/4 deck. Paired with some wider trucks, I think you'll dig it without feeling limited by your board's weight and/or size.
P.S.
off the top of my head, the people I know who ride 8.5s are:
Chris Cole, Corey Duffel, Lizard, and Brian Anderson. Lizard aside, you'll find those dudes are, physically, pretty big.
Tons of guys skate 8.5 and over. I know gipper confirmed that chris cole skates a 9.5 a few years back.
I hope you meant 8.5. I think he was skating 8.3-4 for a long time, then recently stepped up to an 8.5.
He's had two 'My Rides' on Transworld; you can find them with a quick google search