Repowering 18' Potter

[BocaSeacraft]

I'm in the process of choosing a new outboard to replace my old Evinrude 90 (1987) on my 18' Seacraft (1975) and am intrigued by the 2015 Yamaha 70 four stroke. In their performance bulletins they have one bolted to the back of a 1400# center console that's 18'10" long with a 7'-6" beam. This boat and motor combination gets better than 8 mpg at cruise and gets on plane in a bit more than 4 seconds. The motor weighs in at around 265 lbs. I'm having a hard time talking myself out of this motor. Does anyone have experience with a 70 on their 18'? I know several of you guys run 90's on your 20' boats. I run offshore and only run about 22-25 max in any seas 2' or over here on the south Florida Atlantic coast. I don't pull tubes or skiers and 35 is plenty fast. It swings the same size prop as my Evinrude (13.25") What do you think? Yamaha 70? I know one other member mentioned that they used to rig the 20' with 85's in the old days. Will a new 70 be sufficient? I'm turning it over to all you guys who have been running these boats for years. Thanks for your help.