My two cents,,, Saito 91 or YS 63. With the 63 and it's pump you can relocate the tank close to the CG. You will have to put some effort in to keeping the plane lighter. I had both and chose the Saito 91. I put all the gear I knew I was going to use and added up all the weights of the plane. It looked like it was going to end up about 6 pounds. That is really about the limit of the 63 for good vertical. I knew I wanted great vertical so mine got the 91. After having to add one ounce to the tail for balance I ended up at 5lb 15 oz. that should be about perfect for me. My 63 ended up on a 40 size profile that weighs 4lb 7 oz. I did put the Perry oscillating pump on the 91 and moved the tank back close to the CG. Actually I had an old nalgene bottle I used that just fit perfect. I couldn't find a decent sized tank that would fit. Mine holds 12 oz. Both my Saito 91 and YS 63 run great on regular Powermaster 15% castor/synthetic blend.
Good Luck,,,basmntdweller

I think Ohio Model Planes also has some YS 63s in stock.