Check if you have enough height for a 1050 card - I think you probably do, based on the pictures I've seen, but I am not 100% sure.
You will, however, need a "low profile" card (half-width bracket) due to the small form factor case.
275W is very likely to be plenty for the 1050Ti, but it would be best if you could real all the specifications for how many amps are on the 12V rail(s).
SR-71 is correct, though - that's a proprietary PSU - Upgrades aren't available for it to the best of my knowledge.