I use PE parts to get the right size for the periscope guards and then bend them around a piece of styrene to get the correct shape. I've left one link out on the tracks each side which you can see in the first pic.
For this build, I'm going to require a D50878 75mm turret which has cast in check armour but no pistol port. I'm using a Tasca Firefly turret which has the recontoured shell....
... and no pistol port....
However, the loaders hatch opening along with the radio cut out in the bustle is not required here so the first step is to fill in those areas along with the smoke mortar aperture, and a couple of now redundant parts locating holes...
A relatively simple exercise using sheet styrene and filler.
More progress on the turret. Footman loops added to the rear using the same technique as on the hull and casting marks courtesy of Archer depict a turret cast at Union Steel Castings...
More progress. Stock early style 'flared' M3 75mm gun and M34 mount with turned brass .30 cal. Commander cupola needs a little work - as good as the Tasca parts are, their attempt at the hatch locks are rather pathetic so I scratched new ones from scrap styrene. Handle is from fuse wire with a new lip between the hatches from strip styrene....
Still need to add the periscope guard and .50 cal travel lock along with the rest of the vane sight.