yes I agree with those pressures, when I first rebuilt the Flash I followed the BSA book - not good.
Modern tyres (even the old names) require higher pressures, think I read they are made differently now.
Tubes are something I have a thing about, rear has never had a problem but the front always has a very slow leak, like the three tubes I've put in are all porous, and yes I have checked the spokes and changed the tyre, could be I'm just a crap tyre fitter of course