Help determining if NAS will fit in a cabinet

I'm looking to install a cabinet and rackmount NAS for my small business. I'm new to rack mounted equipment and have a question about clearance and installation that hopefully someone can help me with!

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I'm Currently looking at putting a QNAP TS-977XU-RP into this cabinet with these rails

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QNAP NAS Dimensions:

(HxWxD) 1.7 × 19 × 19.9 inches

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Cabinet Dimensions:

600mm overall depth (23.622"), dimensioning on website image shows a max rail depth of 20"

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Rail Specs:

Mounting post width: ≥ 17.8"/451mm 
B. Panel width: ≥ 19.1"/485mm 
C. Mounting post depth: 18" ~ 32"/443mm~815mm
D. The distance between two rack posts is 18.3"/465mm (center-to-center)

So, it definitely seems to me that the NAS will fit, but I don't have the experience to know if it will leave me with enough clearance for cabling or anything else.

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Side note, I was also considering the Synology RS1619xs+, but that definitely seems to me like it wouldn't fit, correct?

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Thanks!