[fpernett]

Go for 77, in competition you will have a lot of security around you and the narcosis shouldn´t be a problem, and reduce the risk of a samba.
That extra 3.4 meters at the same velocity of descent and ascent will cost only 7 seconds more of dive time (4.25 down and 2.78 up), as you end this dive with air to spare this shouldn´t be a problem.

I feel weird giving advice to Eric Fattah in constant weight!!.