Want to replace yam 90hp with yam 20hp

[tryn2lrn]

I currently have a 2007 16' bass boat with a 90hp 2stroke yamaha engine and would like to replace it with a 20hp yamaha 4stroke. I was trying to find a dealer that would do this for me but they don't really seem interested. I have a lot of questions about whether or not my existing gauges and steering will work etc. Has anyone done a swap like this? Can someone with knowledge tell me the possible pitfalls or major issues I will deal with in trying to do this myself.
Thanks

[mitch]

yes a lack in power you are giving away 70 hp why are you wanting to do this it will lucky to get up on the plane .

[tryn2lrn]

Well because where I fish most lakes are electric only or 20hp limited. I never even get to fire up the engine and have to make a special trip over an hour and a half away to run it. That lake is so packed and full of people you can't really run on plane for more than a few seconds safely anyway.
At least if I had a 20hp I could fish more lakes and hear ourselves talk when the motor is on. Maybe even use it for *****ing if need be. Just seems to be a waste to deal with the extra weight etc for something I never use. I really don't care if the boat gets on plane, if I can move at 8-10mph I will be okay with that.
Thanks for the reply