The Enfield valve springs arrived today and dimensionally they are similar if a little over-long. After a couple of squeezes they settle down a little, so I expect them to settle more in service. They are/were made by Terry for the 350 SV Enfield, and the Terry number is V60.
The installed height on the M32 is 34mm, so a quick and dirty test using the scales and a 34mm spacer shows the installed pressure to be about 55lbs. The best of the old springs shows as 52lbs.
Both become coil bound at 1" fully compressed.
Apparently 50lbs is a figure suitable for flat head Fords and should be OK up to 5000 rpm they say. That being the case, I shall go with these, as I think 5000rpm would be a big, and final, day out on this particular machine. They are no worse, and perhaps a shade fresher than the existing set.