Helo there Ria
I did found a 650 V Amrrad cap on ebay. But it nothing close
To 3.4 uF or 3.5uF but 0.75uF
My advice is to contact Amrad tell them what u need
As they are capable of customizing caps any way u want
They also make replacement film caps for radios.
Here the link for u to try and get into contact
https://amradmanufacturing.com/