i have seen 30/50 cals mounted on the division plate. i agree with Jordan the hull is a Mk2. the storage case is this not a t16 thing or a late Mk carrier ? i know models of Mk2 carriers that i have built always have these stowage boxes on the tanks...
as for the engine cover again i agree with Jordan my only other thought if it was not a tank hunter cover would perhaps be Loyd ? but i dont think Loyd covers were tapered.