A scaling recipe, button press by button press for use with a calculator like the app that lives on many phones, to help guess the weight to see if it is going to work or be feasible.
Enter the known weight, times scale, times scale, times scale, equal. Divide by new scale, divide by new scale, divide by new scale, equal.
Shows that a 1:72 Revell corvette weighing about 6 pounds becomes a 2.5 pound boat if you go for a 1:96 version. Or 12 oz if you try the 1:144 kit. If going the other way for a 1:48 version, you end up with a 20+ pound lump.
Once you know the all-up weight of the complete thing, it is possible, with a plastic kit, to weigh the kit parts and gauge what it is going to be able to carry. Or, if going the other way, whether or not you are going to be able to carry it and launch/retrieve ir without joining it in the lake.