Nicely done.
That bitmap does indeed seem to be horrid. I can see a repeated section in three spots on the front glacis plate alone.
With a new template I start by outlining all the UVs onto one layer while also mapping all the annoying stuff (repeated, warped, overlaid textures etc.) onto a layer I call "weird s**t". In general Superfly's work suffers far more than than Waffle's this way. On the other two Shermans there are around half a dozen areas like this. On the Firefly though I had to make three "weird s**t" layers because some of the annoying stuff was laid over other annoying stuff, not just once but twice. I just had a quick count up and there are around three dozen separate issues marked on these layers. It makes large areas of the skin "no go" areas for placing shadows, markings or detail of any sort.
The odd thing is if they were in such a hurry they could have just used the Sherman 75mm template as the base to make a Firefly IC and placed the new gun and radio box parts into the spaces left by removing the Calliope parts. This would have been much less work and made a much better skin. The only difference on the Firefly VC was the huge Chrysler A57 multibank engine which needed a bigger hull.