The original homebuilt was designated S-1C; the C for continental 0-200, but everyone wanted more power so most went with 150 hp. The original S-1 first flew with 55hp engine upgraded to 90 hp Franklin, so if he does it right he ends up recreating the first kind. Adding to the wingspan will be hard for one main reason the top wing with the sweep will not like it without changing the sweep; the CG otherwise woud have to be changed. As to age and ability, I have an aquantence who is the son and they had father /son Pitts. The son told me his father was still landing his on the runway at age 80 and he at 55 would not do it because he did not like the challange and he is a test pilot.