[Arran]

Mylar/poly film caps are definitely what you want to use in an early AC set that formerly used paper capacitors as filters, small value electrolytics tend to dry up faster then larger value ones it seems. Also they are not easy to change in these sets unless you mount them on a separate terminal strip. I know that some guys claim that the old paper filters don't need to be changed, well maybe that was true in 1963, or 1973, but this is 80+ years later, they can and will fail at some point.
Regards
Arran