I have given this a fair bit of thought. I think that when you consider the whole picture, it's a more balanced fight than one might think.
You can't just do the Taffy 3 surface fight. That's about 20% of the whole picture. The Japanese were also fighting air attacks from some 16 Escort Carriers. That has to be factored in. And if you include that you have to include the Japanese Kamikaze attacks on the other Taffys and the IJN subs. They were involved as well.
The Americans win if they force the Japanese to retire. How do you determine when the Japanese retire? You work out a mechanism that I call the Kurita-Meter. You give Kurita a fixed "morale" number. For every bad thing that happens, he loses points. Each CA sunk or crippled, lose points. Each time his flagship is strafed, lose points. Remember, by this point he has had 2 flagships sunk form under him and has been awake for like 40 hours. I've never worked out the number, but it has to be feasible.
American losses count for nothing. If Kurita falls to "0" game over.
If Kurita sinks or brishes past Taffy 3, and can continue, he undergoes x number of turns of air attacks. If Kurita is still AOK, you have a surface action against the 3 BBs Oldendorf sent to cover the east entry to the bay. He kept 3 in reserve. If Kurita beats those 3 he fights the other 3. There is no need to involve the light forces on either side in these battles. The Japanese CA/CL/DDs are overmatched, and the allies are largely (but not entirely) bereft of torpedoes. They have no skin in these fights.
If Kurita beats the other 3 battleships, he gets into the convoy roadstead and earns a draw. His force is surely spent by now. Even if he sinks all the APs and AKs, the next convoy coming to resupply the landing arrives in like 6 days.
The fleet carriers will be back soon to finish off whatever Kurita may have left, then they can take over the Taffys job in covering the beaches.
As a tactical consideration, the Japanese cannot use any of their guns at or below 5" on their CA/CL/BBs. The Japanese were holding those weapons in the AA realm. Also you gotta track ammo consumption. Congrats Kurita, you've reached the roadstead and have 9 18" and 46 6" rounds.