bracket good or bad
 

is a bracket on a 20 sf a good thing or bad.

It's a good thing IF you use the lightest weight motor possible and do some other things to compensate for it's adverse effect on the boat's CG. AND use a bracket with maximum flotation to preserve the 20's limited self bailing capability! Don't waste your money on something like a Stainless Marine or Porta bracket with zilch flotation. I did a post a couple years back listing all the pros & con's of brackets on a 20 based on my research and personal experience.

so if you raise the floor . move the batts .up front and fuel tank below deck it would be ok any other things

I didn't move the batteries on mine, but with a CC you have the option of moving the batteries to the console, as well as moving the gas tank and console forward. Other things include a good 4 blade stern lifting prop and a Doelfin or equivalent on the AV plate and you'll also want trim tabs if you don't already have them. I also had to move trailer axle aft about 12-18" to keep adequate weight on the tongue for stable towing, so that's a good indicator of the CG shift you can expect!