As the owner of a 29 outlaw, I will say that you WILL NOT touch 70 with those engines. My 29 will run 65.2 mph on GPS with twin 330hp 7.4s turning 23p mirage plus props at 4500rpm. To help you I have posted a link to a prev thread in the Baja forum.
Hope this helps
30 Outlaw w/twin 6.2 speed