While it’s common to see guitars assembled from parts across different eras, it’s far more rare with amps. This particular “Vibroverb” is best described as a Super Reverb cosplaying as a 1x15 Vibroverb—even down to the faux tube chart. Surprisingly... it does damn good job convincing you it's real. The amp section began life as a Super Reverb, with the chassis and original transformers transplanted into a superbly built 1x15 cabinet. 
One crucial step was sourcing the period-correct JBL D130F, which is intrinsic to the Vibroverb sound. It’s even fitted with a convincing Vibroverb control plate on the front. To the untrained eye, this presents as a believable mid-’60s Vibroverb, making you wonder whether this was done for the sake of craft or deception. Because the original output transformer would have been designed for a 2-ohm load, it was replaced with a 1968 Twin Reverb transformer, which matches the impedance requirements of a single 8-ohm 15" speaker while still pairing properly with the 2x6L6 output section. The added iron gives the amp a commanding sonic footprint, with excellent headroom and low-end response.
Internally, a handful of components have been updated to modern carbon comp equivalents, along with some metal-film plate resistors on the normal channel. Fortunately, the original Blue Molded Ajax caps remain in the tone stack (with a .047uf value in place of the Super’s .022uf), preserving the core Blackface character. It also has modern electrolytic caps, so it should be good on servicing for quite some time. See circuit photos for further details.
Intent aside, this is an excellent-sounding amp that has clearly surpassed the sum of its parts, becoming something entirely its own. Regardless of its origins, it looks and performs the part convincingly—essentially functioning as a player-grade AB763 Vibroverb that's half the cost of an original!
"I've heard real Vibroverbs sound way worse than this" - unnamed CVG staff member Preamp: 12AX7 (x4), 12AT7 (x2) Power: 6L6GC (x2) Rectifier: 5AR4 Wattage: 40w Circuit: AB763 Transformers: 2x Original Schumacher, 2x Changed PT: Original Schumacher 022798/606805 OT: (OEM from '68 Twin) Schumacher 022889/606834 Choke: Original Schumacher 022699/606803 Reverb/Other: Changed 1990's Mojotone Speaker: 1960's JBL D130F