I have always done big/big and add 2 links chain sizing.

with my recent build with 5800 105 with a compact crank (50/34) and 13/32 cluster, the result was not as good as I wanted in terms of shifting and rear derailler position

My mechanic suggested trying low/low saying that it is shimano's current technical reccomendattion

it worked great for me, not sure how it would work with vintage deraillers and crank/cluster sizing, but will try soon

this method if you are not familiar with it (and I wasn't) is:

put deraillers in low/low combination
thread the chain thru the deraillers and have on the low rings and teeth
size the chain so that it does not rub on rear derailer

here is a video link


ymmv