Upgrading to an RTX 5070 Ti 16GB with a 750W PSU at 1440p? Need advice on this deal (Non-US)

I recently upgraded to a 1440p 180Hz monitor (MSI MAG 275QF) and, as expected, my current GPU is starting to struggle to keep high frame rates at this resolution in demanding games (like Total War, RDR2, etc.).

A friend of mine is offering me his RTX 5070 Ti 16GB for $900, but I think I might be able to negotiate it down to $800. Note that I am not based in the US, so buying locally usually carries heavy import premiums. Getting a 50-series card shipped safely here is always a logistical and financial headache, so buying a known, working card locally sounds tempting.

Before making a decision, I have two main questions regarding my power supply and overall value.

Here is my current build for reference:

CPU: Intel Core i5-13600KF (with an LGA1700 anti-bending buckle)

Cooler: Thermalright Peerless Assassin 120 SE

Motherboard: MSI PRO Z790-A WIFI

Memory: 32 GB (2 x 16 GB) G.Skill Trident Z5 DDR5-6000 CL36

Storage: 1TB Crucial P3 M.2 PCIe 3.0 + 2TB WD_Black SN850X M.2 PCIe 4.0

Current GPU: MSI Ventus 3X RTX 3060 Ti 8GB (I plan to sell this to recoup some costs, roughly ~$230 local value)

Case: Lian Li LANCOOL III (Plenty of space and airflow)

Power Supply: Thermaltake Toughpower 750W 80+ Gold (Semi-modular)

UPS: CyberPower 1500VA / 900W

My main concerns:

PSU Compatibility: Will my high-quality 750W Gold PSU handle the i5-13600KF and the RTX 5070 Ti under full gaming load safely? According to estimated power draws, it seems to have around a 35-40% safety margin, but I want to make sure I don't absolutely need an ATX 3.0 PSU upgrade. I'd be using the included adapter for the 12V-2x6 / 12VHPWR connector.

The Deal: Assuming I can close the deal at $800, is it a good upgrade path from an 8GB 3060 Ti considering I am jumping to 1440p? If he stays firm at $900, is it still worth it given the non-US market context?

I appreciate any technical insights, experiences with the 5070 Ti on 750W units, or overall advice on whether I should pull the trigger.

Thanks in advance!