Pretty sure the WW spring would do a fine job, Paul. But Tinny's kits are excellent and are a known good performer to you, so go for that. The quality of the spring is excellent and the newer design two-piece spring guide very nice.
Don't lose heart with the '35 project. I hope your quest for a piston is successful. You will get it right and the resulting rifle, with that lovely stock, will be a cherished member of the family for many years. Does yours have the later piston (lighter and giving more stroke) or the earlier one with a synthetic head convertor fitted?
If your search for a piston isn't successful (and I'm sure you will find one, either here or at somewhere like Protek), one of our highly skilled engineers, like NickG, might be able to make and fit a new piston rod to your existing piston?
