The '81 Silverwing is based on the CX500D. 80-degree V-twin, single camshaft OHV 4-valve per cylinder, 5spd, wet clutch. The CX's initally came out with mechanical cooling fan by virtue of the camshaft coming through the valley, out through the front, to an aluminum hub with a composite fan, no fan clutch. The early CX's had a little issue with the cam chain tensioner which was addressed in manufacture prior to the GL version... and later models nix'd the mechanical fan and went to an electric fan, which resolved not only any remaining cam tensioner wear, it also solved the long-term fatigue of the composite fan.
The CX's rear suspension was twin spring-overs, but later became a centrally-mounted monoshock linkage design. Initial CX FRONT ends were basic springs/oil dampers, but with the GL, air-charged adjustables appeared.
The GL500 Silverwing was more-or-less born as a 'trim package', that evolved a bit... they had a nifty seat setup, where it could be a solo with integrated trunk, or switched to a two-up. Saddlebags were part of it, as was a fairling.
It was successful for those who wanted something that was 'smaller' than a BIG bike. They were nimble and comfortable in most realms, but they were hindered a bit in high speed comfort due to low gears. The V-twin was bulletproof (My '79 CX-D has over 300,000 on it!). With only three chains in the engine, it really didn't have much to go awry... the water pump seal is somewhat of a bugger, and contrary to most reports, it CAN be replaced without pulling the engine. The valves are INCREDIBLY easy to adjust, fuel capacity is substantial, and it is in no way 'cramped' to ride. LOTS of ground-clearance, so you won't worry about dragging pipes, pegs, or banging curbs.
It is torquey... you won't be needing to wrap the throttle and drag the clutch to get around. Crawling up steep driveways, stoplight to stoplight, navigating suburban sprawl, and maneuvering through parking lots is easy... excellent low-speed manners in all respects.
The gears are low. At 55mph, in top gear, you'll be at 5k. At 78mph, it won't buzz you as bad as say... a KZ400D... but it WILL eventually fatigue you. It is also light enough so that being kicked around in the slipstream of freeway traffic will be tiring.
I always thought that an ideal suburban commuter-bike, would be about an 800cc version of the CX/GL500, with a modest fairing, removable lowers, pannier bags and trunk, a little more spread between the ratios with a 6th, and a highway ratio of 4600rpm at 80mph... and mebbie an inch and a half more wheelbase.
As for a collection-add, if it's in good shape, YES.