Over the years there has been conversation about building up an AA-5X with conventional gear, but most opinions have said that in the US you would never get it approved today. If you check the Grumman Gang archives you might find some past comments. When “Mean Gene” Plazak got the AA-1 STC, it was a much simpler time to get something like that approved.
I have owned an AA-1B since 1981 and put a 0-320 in it shortly after that. I had thought about putting the Taildragger STC on it, until I got a chance to fly one. The gear is so far forward that you must fly it off and land 3 point. I talked to Gene later about that and he said the FAA forced him to move the gear out to reduce the chance of nose over. Gene past away a few years ago, and last I heard someone in NY state bought the STC.
So for the AA-5X, you have a lot of different dynamics in play. You have a longer fuselage, so what kind of beefing of the tailcone would be required to support the tailwheel? If you can find a set would Gene’s brackets and main gear legs work on an AA-5 (will it support the wight and place the gear at the optimum position for the -5), or would something new need to be engineered, designed, and built?
My feeling is that should you go down this route, your kids might be long out of the house before you have such a project flying. You might be better off looking at the Home Built world (RV-10 and many others) or say a trusty but slow Stinson, Piper Pacer, C-170 or 180, ect.