weight balance?

In principle, lighter is better. F/R balance is good, but polar moment of inertia is just as important. That is, all other things being equal, you can turn quicker with the weight concentrated in the middle of the car, as opposed to being at the extreme ends. Unsprung weight is also a factor -- this comes into play when you go to bigger brakes, bigger tires and wheels, or upgrade to an 8-3/4 rear end.

The increase in grip from wide tires probably offsets the extra weight. But otherwise, any weight you take off is gold. Since there is probably more opportunity to take weight out of the front than the back, it also helps balance.

The only thing that might not help would be if you, say, removed the spare tire and the back seat to save weight, and did nothing else. That would exaggerate the front weight bias.

But moving the battery to the trunk is a net gain. And any aluminum engine or engine compartment components -- heads, intake, radiator, master cylinder, water pump...