Hi Mate, Welcome.
An interesting want list....From Special to Rover to Vortex! A nice diverse collection.
I dont know much of your Tac, but assumed also it would be a full crank.
As for your little beastie, Yes the cowl is easily enough explained as you said.
At the Risk of toe treading, Your 18 is actually an early Model 5 series 2 judging by the serial.
AC is actually the intersecting serial between the model 5 S1 and 5 S2.
The image is a little hazy in the axle area, but I can see no axle mounts, making this a Series 2
The cowl and tank is correct style for early series 2 with exception of the Cowl sticker. This sticker was used on the 2a Some Model 4 Automatics and early model 3 Rotomo.
The Line/option code of 0 is unusual and would have been more suited to an early automatic.
I cant see clearly, but the cap looks green? If this is the case, then this tank cowl assy was off an auto. (But still accurate for your Model)
In anycase, even with the changed cowl, it is close enough to a correct Early Model 5 Series 2.
Filter is also correct, but snorkel has been shortened ...cant see the throttle control.
Very soon after your mower was made they changed the recoil Starter and introduced the big black choke assy both of which saw out the rest of the Model 5 series 2 run.
Anyway, shes a very nice tidy Machine. Thanks for showing us...
