the major problem with both the Promod & Mono kits is the aft fuselage - where it meets the base of the vertical tail - it's too wide for the scale. If you are one of these modelers for detail, Belcher Bits of Canada makes a corrected tail conversion kit, and conversions for PBY-6A, & the eariler PBY-2, -3 & -4. It's a resin aftermarket kit, and I doubt it if it's still in production. Other than that, cockpit & waist guns are good for detail.
The other advice i can give is place a brass rod/strip thru the wings to provide added strength to keep them straight over time (so they dont sag down). But considering, when built, it's a VERY impressive kit. I recommend a book from Squadron/Signal Publications in detail & scale Vol 66 - PBY Catalina - EXCELLENT resource!!!!
Good luck mate!