Yes, the 1.9s all got the 'good' alloys, with the possible exception (rumor) of the 1.9 n.a. exhaust valves not being quite as stout as those in the 1.9TDs.(?)
As far as the trans, sometime in '83 the Vanagons (possibly coinciding with the waterboxers' arrival?) were equipped with side shifter trannies, instead of the nosecone linkage. Get all the 5-speed's linkage pieces you can; they will, along with the advice from
libbybapa, help you get it working in your chassis.
BTW at least a few 5-speed gasser Vanagons were sold in Canada; several of my dealership tech buddies mentioned seeing them here in SoCal, when servicing Vanagons for Canadian tourist customers.
As to relative gearing effects... it all depends which 5-speed and 4-speed you're comparing
http://volksweb.relitech.com/helmut/GEARBOX.HTM The combinations of 1st gear & final drive ratios of all of the gasser 5-speeds listed, look to be a bit higher than any of the 1st gear/final drive ratios of the diesel 4-speeds, so that would probably work your clutch harder, especially if you have a really steep driveway!
If you offset the minor theoretical loss of your 'digger gear' capability, by swapping from a '82 Vanagon diesel's 1.6 n.a. (71 lb/ft @ 3000rpm) to a 1.9 n.a. (c.100lb/ft @ 2400rpm) or a 1.9TD IDI (c. 110lb/ft @ c.2000rpm), you probably won't notice the difference of the 5-speed's higher initial gearing, but once underway, you'll probably like the closer gears a lot. That and lowering the engine's cruising RPM could bring some fuel savings and add to your enjoyment of your Vanagon.
Have fun.
J.R.
SoCal