just about the "Redwoods"... no problem to stretch a bo2 to extremer height, isn´t it?
That´s one of my "urwald" (jungle) biome trees, reworked by stretching about 20 blocks up in height (wrong biome, I know, was just used as its the centrum of testworld for easy showing ...):
How to do?
Simply using BetterBOB and clone the upper parts to 10, 20, 30 blocks up (or whatever height), doing this task layer by layer.
After this has been done, clone one layer of the straight part of the tree at the lower part up, by duplicating it 10, 20 or 30 blocks at once, just whatever you choosed at the 1. step on top.
Save the changed bo2 at a new name and that´s it
Example of stretched to real redwood size (up to 60 blocks height):
Also this may be done by simply using TC´s possibilities:
Upper image = real world, lower = TC