ZZegna now has 2 cuts, a drop 8 and a drop 7. The drop 8 has very soft shoulders and tapered trousers. Its jacket would not look anything like an RLBL. I haven't had a chance to handle the new drop 7 model, but am guessing it would be similar to the discontinued City model, which had a more structured look. I would guess that's one you tried on.
The mainline E. Zegna currently has 2 base models, Torino (drop 8) and Milano (drop 7). They're almost the reversal of ZZegna. Whereas the ZZegna drop 8 has soft shoulders and the drop 7 (presumably) structured shoulders, in the mainline it's the Milano with soft shoulders and the Torino with strong shoulders. However, I think the RLBL is still most built-up for shoulder padding.
To answer your questions: No, ZZegna does not fit similarly to the mainline. ZZegna is more contemporary, so it's likely shorter and tighter. As for the mainline, since there are only 2 models, you won't really find anything similar to Torino other than, well, Torino.
One recommendation, if you're looking at the ZZegna, is Canali's 17xxx lines. Canali has a bunch of models (11xxx, 13xxx, 15xxx, 17xxx and 18xxx I think), and the 17000 lines have a somewhat structured look, while also being slightly trimmer. I would also suggest looking at Paul Stuart, Samuelsohn or Corneliani if you can find them. The drop 7 models should all have stronger shoulders.
If you're 6'2", you're likely going to need to wear tall sizes. Instead of "R", look for suits with "L" instead. Sleeves can normally be lengthened; it's the jacket length that can create problems.