Here is my list of things to think about.
What bottom thickness do you think you need, .160, .190,.250 etc. Thicker the bottom, the more weight which might influence engine size, thicker the bottom the less chance of a hole.
Same goes for bottom width, 5.5', 6',6.5' etc. Wide bottom equals more room, but more weight.
How many strakes do you need, 2 or 4, the more strakes the better the turn.
I believe that a boat less than 20' will have some sort of floatation foam, this adds weight, takes up room, and if it gets wet will add weight.
Is the boat a cab forward design, cab forward will give you more interior room, but reduces room in the bow.
If you are getting a thicker and wider bottom, consider the 6.0 .There is also the 6.2 and the 6.2 with a super charger, basically the Corvette engine.
If money is not a concern, take a look a P-weld boats, A member here has two I believe a 20' and a larger 24'or so at least one has a Yarnmar diesel twin.
A Hamilton pump will probably add $3k or so. The AT rock crusher is a fine pump, much better than the original AT.
Get a tower, I wish I had one.