If there’s a fly shop near you I would think they would let you try a couple different lines before purchase.
If no fly shop I would start with a 7 weight line and go from there, but I would try a line that had a mild taper. For instance a Scientific Anglers Amplitude Trout has a longer weighted portion than the Amplitude MPX. You might hear something like the Amplitude MPX has a shorter ‘head’ than the Amplitude Trout. The Amplitude Infinity has a head between those two.
And I only looked at the one website. Rio or whoever will have similar charts for their lines. They all work, and if you fish them enough you’ll develop preferences that probably don’t have anything to do with the weight.
I would also order from somewhere that will accept returns! Then if it doesn’t work out you can send it back.
