Aguila,
You have the pre-Baja series hull like the second photo that I posted. From looking at the pictures I think that the factory was adding on the extra lip at the chine up towards the bow to deflect the spray down, maybe even add some lift.
My side windows are different from yours. I have the the style that was installed on the 26 footer and the mid 1990's model.
The frame on mine has been redone by the previous owner and the interior has been lined with carpeting to combat that humid feeling that you might get without it.
The 115 Merc is adequate but not a lot of extra power when I have 3 aboard along with the bait tank filled with water. If I happen to have 4 guys, I feel the weight but the boat still gets up on plane without a problem. I just lose some speed at the same RPM's
I'd opt for the 140 considering that you will be beach launching and will be in need of serious power to get you out of there.
What ever motor that you choose, make sure that you have good dealer support for warrenty and parts issues.
I see that you already have hydraulic steering which is good.
It looks like you have an aftermarket motor bracket. Is it strong and rigid?
I was expecting to see the factory bracket like this 23 footer is set up with
Here's a Bayrunner that these San Diego boys rebuilt last year.
It's worth a look
AluminumAlloyBoats.com
If you are unsure on the year of your hull and you still have the hull # on the transom, the year is within those #'s
On mine it's HUL023###889 which makes it a 1988 or '89 hull
Good luck on your project