You have a lot of ambition, but your choices are limited. Verlinden and TW both make interiors for Tamiya's M4 75mm dry, also called "early." TW also makes an "M4 late interior, wet stowage," but I have never seen it -- this is marketed for "Tamiya kit" but no one makes a late M4 wet stowage, so I assume this is for the M4A3 75mm wet stowage. Anyone have this kit???
CMK is also promising an interior for the Tamiya M4, so there is another choice on the way.
A word of warning -- not all Sherman interiors are the same. While the driver/assistant driver positions are largely the same in most, the fighting compartments are very different. Ammo stowage, accessories, etc. are different. Even the turret baskets have different arrangements. When you factor in dry/wet stowage and/or 75mm/76mm/105mm/17-pounder it gets even more complicated.
AJ -- just because the hatches are open doesn't mean you have to have an interior. If you put a figure in the hatch, you can't see much inside anyway.
If you want to try to convert or scratch an interior, I suggest you get Hunnicutt's "SHERMAN: History of the American Medium Tank." I'll warn you that it is out of print and you will be lucky finding one for under US$100 used.
Sorry for all the negative vibes ... and good luck with your projects!
