Should be. It all depends on how it has been cared for.If you jump up in size a little bit, to a 9.9hp, it will run smoother because it will be a 2 cylinder engine.
The 6hp is a 2-cylinder as well and will run quite smoothly... They're good little motors, BUT make sure you pay no attention to the 100:1 fuel mixture sticker on the cowling (if it's still there). Also, inquire as to whether the previous owner ran it at100:1 or 50:1. The 100:1 that was recommended at the time was rescinded in the early 1990s due to powerhead failures related to too little oil... If the motor has been run a lot or stored for a long time with only the 100:1 mixture, it may have issues. A compression check is never a bad idea, and neither is a quick check of the lower unit oil for water... Those lower units were terribly robust - good enough, but wouldn't take a ton of abuse.- Scott