Car Batteries: About ready to use LiFEPO4 in place of PB?

The ChevOldsmoBuiac has been having some trouble cranking on cold mornings. The battery is just barely 5 years old, so a replacement maybe in order. I cleaned the battery terminals this weekend, and the slow turning hasn't re-occured, so I'm hopefully that was the root cause. In case it is not, I was wondering if LiFePO₄ batteries had gotten big/cheap enough to use as replacements. It looks like we're getting into the space where that's feasible.

The 1990 olds cutlass ciera OEM specification is for a ~650 CCA battery. A 600 CCA LiFePO₄ is about twice the price, and will need some work to adapt the battery terminals. However, if it really does last 2-5 times as long, it would be the last battery I bought for the car.

While googling, I found another person who suffered the same fate and described the requirement to remove the front brace as a "Jigsaw puzzle". Was there truly no way to put the brace elsewhere?

In terms of repair work, the biggest travesty with the A-body Cutlass Ciera is that their huge engine compartment, which would seem to make repair easy, is belying close tolerances and poor organizations of individual subsystems, and an annoying predisposition of the entire vehicle to drop paint and rust. At least the parts are plentiful and cheap.