You may want to take a second look at that airplane bhady before you go to the trouble of an engine change and there is the possibility that a big engine may not solve the problem. Not the real problem in some cases and this had nothing to do with being heavy or a high wing loading.

When the fellows convert some airplanes to a tail dragger what some times happens is the main gear they use is much to short or a tailwheel is much too tall and worst case scenario mains are too short and the tail is to tall.

When this happens after plenty of speed is attained but the very level deck angle will not allow the wing to rotate to sufficient angle of attack to attain a lift off. Once that tail wheel hits the ground that is it you cannot rotate any further no matter how much power you have.

Now I am not saying this is what happened to you but you just might want to take a look at the side of your airplane on its wheels will tell many stories and may save an engine change. Didling with different gears is easy an quick.

John