1977 Vintage Port

[hoodinii]

First time poster.

I own a 1977 Vintage Port by Smith Woodhouse.

Is there any way to find out the value of this port, and also how long can this port be aged for best drinking?

Here is the information on the bottle.

Smith Woodhouse
1977 Vintage Port
Bottled in 1979
Shipped and bottled by Smith Woodhouse
Oporto
Produce of Portugal

Any help would be greatly appreciated,

Thanks,
Rob W.