WE did same thing on VW Bug engines in the 60s and 70's.
That way you could remove the valve covers and not have to replace and scrape the cork gasket if it was necessary to check valve clearances.
Valve adjustments were at each oil change 3000 miles this way the gasket could be re-used several times.
The dealer I worked at used 3M Weather strip cement. Did this for many years.
The trick on Model A is to use about 2 foot lbs or so on the bolts.
Over tightening smashes the cork.
VWs had those wire spring clips on the valve covers so tension was always the same.