After weighing engines i'm sticking with the super tigre G4500. the weight difference, using a different engine to the G4500 meant a good 2+kg of ballast. With the super tigre it's 1kg.
For machine guns i've got an old plastic williams kit one (taken off an old model) i'll tart up and install on the front.
The rear parabellum is harder to obtain 1/4 scale and really startled how expensive these plastic kits have got.
So started making one (as per plan instructions) My efforts obviously aren't to the same level as you guys, but my first attempt I'm actually quite pleased particularly as it's cost 'nowt'.