If that is the one that is off the plate to the side of the block? I would just cap it off at the source...DO NOT tie it in to the Brake line........AS that will have oil pressure that will blow oil in to the vacuum booster.... The blanking plate pictures is off a 80 Ish- 90 ish 1.8 EFI or CIS engine as that is where the mechanical fuel pump goes for Carbed Rides.
New:
Old new Side by side....
The hose isn't needed for the Vane type, and the plate on the block You can use a Rubber Cap with a hose clamp, but I would be replacing it soon with the proper plate as the oil pressure in the engine will blow a hole in the cap...
Plate numbers for the new picture.
9 Seal 028127311A
10 End cap 063 103 113
11 Spring Washer B8X15 N01224110
12 Socket head Bolt M8X18 N0147123
ETKA is a good source of info.
Parts catalog Volkswagen - ETKA Search Parts by original number Volkswagen, market EUROPA
volkswagen.7zap.com
The only issues are that early models are usually a lot of blanks,,,but using the Europe or RHD pages and looking at the Caddy (VW Rabbit Pickup, or Golf )
has a lot of the missing pages. Just have to remember that the English is RHD vs LHD and a lot of the VW MK1 parts are used in the Cabriolet up to 93, but the big differences are in the body and interior as the Cabriolet was European Built and not Westy or American... as in 84 the lines merged from Rabbit to Golf.
I suppose that after thunking on it after posting you can carefully remove your plate, and use a piece of tin .020 at least trace the outline of the plate, drill Holes to accommodate the screws to blank out the hole for the hose and make a new seal out of paper seal material and Seal the hole....Better in the long run than a rubber cap... as it may blow off under the pressures in the engine.
Trace the outline of the plate cut two holes for the Screws,,,,,then place one seal on both sides of the Tin...One for the block and one for the cover. Or run to a wrecking yard and take a plate off the Rabbit, Cabriolet, or Golf as I think they are the same as the 1.5 but can't verify that.