I am a firm believer in a head gasket with all the nuts torqued to specs.
Timing is going to affect top speed, acceleration, throttle response, head temps and jetting. If it fires too early your going to heat soak the head and probably seize or if it fires to late it is going to not properly burn fuel which would lead to poor performance. I would read up about timing and get a light. I kept buying cheep lights off amazon, but they kept burning up. I went to the auto parts store around the corner and grabbed a decent light off the shelf, blew the dust off it and had the parts guy ask me what in the world I needed that for. However it was worth the investment. You have to listen to what the bike wants. Just because some people run a range that is usually a good starting point but every bike is different. You might a couple Jets higher or lower than a person with the same setup. You would be surprised how much more power a properly timed bike with correct points gap will have.