Gus, a lot will depend on your citizenship status. If you are not a US citizen you cannot document the boat, but you probably can get a Texas state motor vehicle registration for it. You'll need to ask Texas about that, and ask them about how to bring it into Texas as well. A Texas state registration is probably required if you are residing in Texas and the boat is in Texas' water for more than 30 days, all states have similar rules.
The other option is to title in in Brazil and do whatever is necessary there, then bring it in under a visiting status--but IIRC that would limit you to one or two years, the same as any other alien cruiser who wanted to visit in the US.
So, your visa staus, residency and citizenship are going to be the criteria and those will define which options you have for it. No, you can't just "bring it in", since even for Texas registration, you'll probably have to provide previous evidence of good title and for a post-1972 boat that will probably mean some kind of title work from Brazil.
I'd call or email the appropriate parties to get the direct facts, and then before going out for the boat, send them letters and ask for a WRITTEN reply so you "have it in writing" before you actually have to do the paperwork.