RE: Lt-40 as taildragger
Rep, that's the prettiest LT-40 I've ever seen. They're usually as homely as a school bus (but they are a good plane).
The only case I know of someone trying a free pivoting tail gear was a disaster...uncontrollable.
I agree with Rodney and Russianflyer...keep it simple. No need for a tail wheel on grass. Either run a wire up to the rudder for steering as above (w8ye and Rf), or even use a fixed skid. As long as it has some flex and extends backward some, you will be surprised at how well it steers on grass with just the prop blast on the rudder. I've done this with a few of my own planes and never regretted it. You can turn tighter on the grass by making it steerable, if it matters to you. It doesn't to me.
Jim