First time poster so if this is in the wrong place I apologise in advance! I'm thinking for a project to create a Beutepanzer ISU 152, with German cupola and Thoma skirts. How easy is it to fit a Pather D/G or Panzer IV cupola to the mentioned soviet beast? Considering using the Tamiya ISU as a base vehicle. Apologies if this is a lot of questions.