What the string is made of will also affect the sound. I believe in the 50s and early 60s strings were usually pure nickel and usually higher gauge than modern strings. Now strings are made in lighter gauges and you can get nickel plated steel or pure nickel. Steel being a bit brighter and pure nickel being a bit warmer. I tend to use Ernie Ball Rock n Rolls 11s.
If you're playing surf I would definitely go with higher gauges. A lot of retro types are into flatwound strings too (think early George Harrison). I've never tried them so I'll let someone else share their opinion.