I've had ice lift the dip stick in the past, as sap runs and the ice floats on top. I then removed the dip stick and stuck it in backwards so it is up in the air. You could also plug that hole and not use the dip stick.
For valves, most are available from aftermarket sources. You can also get adapters changing from most types of connections to another, even to NPT. What does your tank connection look like now? a picture may help. Also include a ruler in close proximity to the fitting for reference. With that one of us will likely be able to give you an answer.
I have 7 tanks and only 3 came with the valves but I now have SS butterfly valves on all. A butterfly valve is a type that will not self destruct if it freezes but you need to thaw one before you turn the handle or you will damage the seal.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.