5V PSU is fine; overkill, but fine. CPC do sell DIN rail PSUs which are more costly, and lower rated but would give you an immediate solution to mounting this in your enclosure (I'm not going back through your pics but imagine there's a bit of rail spare in there somewhere?) There's one for a tad under £20 in CPC - more expensive, but either would work.

If you wanted to offset the cost I can throw a couple of 10,000uF / 160VDC (I think... cba to go to the shed at this time to check) caps at you - I just keep tripping over them, and having bought a job-load of them there's not many projects that they are suited for. But I think you'll be hitting CPC anyway for the bridge (I've nothing suitable).

I do think the choice of transformer voltage is not the best - as Jazz said it puts you at the bottom end of the next-level of stepper driver voltages (cheap - upto 50V, next level upto 80V and then around 110V before mains), you're too high to use the 50V drivers and so you're paying for 80V drivers and not really exploiting this. 2x45 wired in parallel would present around 60V which gives you a bit more bang for your buck at no extra cost. I'd go for... https://airlinktransformers.com/prod...ange-cm0300245

If it helps - I run a 2x50V 800W toroidal primarily on a Sieg but I can and do slave the Denford star mill (probably similar motors) from this. The choice of transformer was a Maplins clearance sale bargain, but it was close enough to what I wanted.