For The Love Of Port

I have inherited a 1940 bottle of Boal. The details are as follows: Manuel De Sousa Herdeiros Crop 1940 Maturity Grade In oak casks Bottled in 1978. Nos 1 to 20,769Carrafa No 10,149 The bottle is sealed and is in good condition. I know nothing about madeira and would like to know - do we drink it, s...