Thank you, evert. As you say, I'm sure it will work, as in it will function, but might be a little shy on power. But I was thinking if the TbT spring is a little beefier than the OE and with a little extra preload, maybe? If I ended up with something around the 8.5 to 9ft.lbs mark, but shooting very sweetly, that will do.

I'll certainly check out the suitability of the springs for old Meteors and 25mm Gamos too.