It sounds like AC: Origin's performance tends to be greatly limited by the CPU, supposedly due to the inefficient DRM that it uses, so a CPU upgrade might help a bit. The per-core performance of the 3770 isn't actually that much faster than what you have though. That CPU's main benefit would be that it adds hyperthreading, though I don't know how much that would help this particular title. Something tells me that you might have difficulty getting 60fps with any CPU compatible with your existing motherboard and RAM in that game. Given the fact that your performance is likely currently more CPU-limited in that particular title, you could probably turn many graphics options up further without affecting your existing performance that much. Running the game at only 720p low is unlikely to help your frame rate much compared to 1080p at more moderate settings.
Honestly, I don't think any of those upgrades would provide a huge improvement to gaming performance though. The SSD would do next to nothing for frame rates, though it would improve load times of any games installed on it, along with general system responsiveness if you install Windows and your applications on there. And it does sound like you could use some more storage if you only have around 400GB now, on what appear to be older, slower drives.
The 1050 Ti might allow you to turn up graphics settings a bit higher in that game at the same frame rates, but I wouldn't expect much higher frame rates from it if the CPU is limiting performance more. Personally, I wouldn't bother upgrading from a 1050 unless the new card offered at least 1060-level performance. Your PSU's capacity might be a little low for one of those, but a new generation of lower-powered cards will likely be available by this winter, and it might be worth looking into what kind of performance those will have to offer in the sub-100 watt range.
As for the RAM, nearly all games can still get by well enough on 8GB, so long as you are not heavily multitasking with web-browsers and other things open at the same time. More RAM will be needed eventually, but it's priced relatively high at the moment. Plus, if you eventually decide to upgrade your CPU and motherboard to a faster, more recent option, you will need to replace it with DDR4 anyway.