I wanted to lay in the layers of mat and 1708 against the hull maybe several days before putting in the core.
Maybe I was not clear: is there a reason you want to thicken the bottom of the boat's inner laminate? Unless you have ground away a large amount of glass, you want to put the core directly onto the old inner hull glass using the 954. After this, then the layers of 1708 on top of the new core--to form the new deck that you will walk on.
Generaly you want to do as much as you can when the layer below is still not completely cured to get the best bond--"green" is the term used. With Resin infusion you lay in all of the dry components, and then create a vacuum which sucks in the resin all at once. When boats are laid up, there are layers of mat and roving laid in concentrically then more layers etc. You don't want full curing between layers.
For laying in the balsa core, using vinyl ester resin is a good choice. Coat the core with resin, (see article), and a light coat of resin on the inner part of the hull where your going to place the core material. Then trowel in the 954 bedding compound, lay in the balsa core.
Yes, I would do the boat in sections--doing the bow first, seems best for logistics I would trowel in the 954 and lay the 3/4" balsa core directly on it. Then weights on top to let it go off. None of the 954 will come thru the balsa. I would put a thin layer of mat (3/4 oz) between the layers of balsa to get better bonding. Then put in the second layer of 3/4". However, it this case, it might be better to put in the 1 1/2" core after the first layer of 3/4". The 1.5" core would again go directly into the 954.weighted down and allowed to go off. (again coating both the core and hull with vinyl ester resin) I would bring the mat between the two layers of 3/4" sweep up the forward part of the 1.5" this would give a better bond between the parts of the floor.
After you have all of the balsa done, you will then begin to build the new inner skin (the deck you walk on).. You may want to use the less expensive polyester resin there. If you have some of the vinyl ester you can use it for tabbing. It will be 1708 mat side down, mat, 1708 mat side down. Again logistics of access may dictate how quickly you can work and still be able to move backward in the hull. The last layer of 1708 and mat may be swept up on the side of the hull a short distance. You will put a layer of mat on the surface for the smoother finish. The final floor finish which is similar to the original is to thicken resin with cabosil so it retains peaks as you roll it on--that makes a nice finish and non skid deck. An alternative is to finish with one of the nonskid paints.
Epoxy Works which is a free publication of Gougeon Brothers, Inc., us a fantastic resource, even if you are working in polyester or vinyl ester resigns.
Here is an article dealing with a small section of damaged core
From the 5th photo on down, is where you want to pay attention.
The "BoatWorks Today" are a fantastic resource. The one linked to, is replacement of plywood core and preservation of the original deck surface. A lot depends on what the surface is, and how the job is being done. But there are some significant differences there and with what you will be doing. All of these are resources which should be used and applied to your work.
Here is a piece on working with vinyl ester resin and a light boat repair. You have to read between the lines as to what applies to your boat. But note that in general you want to put the new balsa onto the old skin. Keep the boat light. The bonding putty is what fills the gaps etc which are going to be present even after grinding.
Looking at the LBI web site, it appears as if they have all of the materials you need. except the balsa. You might price out their products and shipping. It is in CT, but having all shipped at once might give best shipping price. Maybe things like the 1708, mat and polyester resin could be obtained locally.
