Hello Piotrek, taking a look at photographs it seems your aircraft needs both a solid nose and adjustments to the upper fuselage to remove/cover up the gunner position, not quite straight forward to do I am afraid to say.
The nose glazing does not use alpha cut windows as far as I can see so would need to have the open areas blocked up, most likely I think a new nose would be the best answer. The turret parts could be removed, however, the hole would need a new mesh made to blend the fuselage to the rear areas, each of these would then need to be mapped to the existing texture and as there is no template available as far as I know that would have to made or a existing skin modified with new lines and such to help it blend in with the existing scheme.
On top of that are there Lods? I have not looked but if there they need to be adapted for the new solid nose no gunner version.
And then there is the new slot and any changes to FM, hooks and so on and so forth.
Providing the changes are all I can see for the 3d then maybe not a mammoth task, however, do not hold your breath waiting for me or someone else to do it at the moment, maybe I might add it to the very long to do list.
Take care.
Wishing you all the very best, Pete.