Umarex Notos compared to PP750

Hi Everyone.

I'm just going down the rabbit hole with the PP750. The Notos isn't available in the UK. I was wondering if aftermarket parts are able to be used on either gun?. I was looking at the FX barrel and the plenums with a gauge offered by C88machining. The Buck rail AR grip also looks nice. I saw that people have fitted Wildcat cocking levers to the PP750. It looks a lot more substantial than the bent steel plate lever...

Any wisdom would be gratefully received