My 1986 car didn't have any bungs or covers, just bits of Gaffer tape over the holes. Works for me.
If you do decide to make up some blanking plates (and why not? seems like a good plan) then be sure to give the speedo drive cable a nice easy curving route up to the speedo, if you force it into too much of a tight turn it will quickly break.
While you've got the cover off, do yourself a favour and fit a quick shift gear change lever. Only 38 quid from Rally Design and it transforms the feel of the gear change.
