Post your dyno chart including Air Fuel Ratio. I think 61hp from a Stg1 88 is about right. Why did you dyno it in the first place? Just for curiosity sake or was it going like a slug?

$350 for a stage 1 tune is a bit excessive - thats 2 hours dyno time. The reality is that they will already have a canned map for your combination and they will just download that, do a coupla pulls and call themselves heroes.

Ask yourself:
Does it ride OK now?
Do I need more power?
Do I need better economy?
Can I afford this?

If I was you I would tell them to get fucked. If the engine is a bit rich then your economy might be down a little but it wont hurt the donk.

Alternatively make them guarantee that they will get 71hp or its free.   I would be surprised if a tune on a stage 1 bike can give 18% more power.

BTW I would have re torqued the rocker bolts and checked again in 2000 ks. There is a good chance that would fix it - for about 10 mins labour...