How about the new 13HP "predator" (Honda clone) from harbor freight?
http://www.harborfreight.com/predato...nia-68306.html
The Blu Max wasn't real good, so they switched to this one.
I installed the 6.5 HP on my Yerf 3203 and have 0 issues with it. Starts in 2 pulls or less.
Lots of aftermarket parts available if you wanna beef it up even more.
Also, HF has a 25% off coupon floating around for New Years Day only.
Or 20% off anytime you're ready.
http://www.ebay.com/itm/Harbor-Freig...item336ff46c0c
As for the GY6, that's all a self contained engine and transmission. Your TAV will not work with it. The engine mounting is WAY different. Would take alot to switch over IMO.
If you search Youtube, there's a guy that has the 13 HP Honda installed on his 3203 already.