As an add on kit for Panzer IVs , why not make a Whirbelwind turret ? You seem to have a handle on designing the 20mm guns in your 250/8 kit and the turret shouldn't be too much harder to make than the 250/8 turrets , just larger . Could be a nice one sprue kit , 2 piece turret , 4 guns , gun mount , seats , ammo rack , gun sight and three man seated crew . I've got the resin Company B one , and although it's not a bad kit , it does take a lot of work to straighten out the one piece resin turret and untangle (
) the white metal gun barrels . Not to mention having to butcher figures to try and get a crew in that turret