[hharney]

Great questions, here are some facts about your ideas

Riley made the 520 converted Skymasters and they were all pressurized cabins. From what I have heard the climb performance is greatly improved and if I remember it was about 30 minutes to FLV 200. But this performance came with a lot of restrictions, because there is only one MOD that provided a GW increase to our birds and that was the Robertson STOL Kit. I am not sure it added anything to the G and H models as their GW was already 4700# and not many Robertson late models were built. So we are stuck with the factory GW. This made the Riley 520's pretty heavy with full fuel. Like 250# useful if I remember.

The other option is the Owen Bell 550's. Those can be STC'd with just changing one engine or both. There are only a handful of conversions out there with this STC and I'm not sure if the conversion is even doable today. But with the cost of the conversion you could have another aircraft that has more performance, more seats, more range etc.

There are a few MOD's that you could do but your trading dollars for quarters.

The Skymaster is a great airplane but it has it's limitations and no matter how much we try to go faster, climb better, land slower, etc it's still just a Skymaster. You need to really look at the mission you have and decide what airplane will fit that mission. It may not be a Skymaster. If you insist on flying a Skymaster, like most of us on this forum, then you just accept the performance you get and keep smiling. They are great planes for what they can do but we can't make them do what they won't do.