Turbo prop conversions
IO540
I have no experience of the Piper Jetprop but because of the reasons you give the P210N conversion is still certificated at the same weights and speeds as the origonal piston type.
The VNE is now the top of the yellow arc at 167 as opposed to the pistons 208. This is not a problem as the a/c is rarely flown at low level due fuel flows, and at the normal high teens flown, TAS is 205 ish.
The conversion includes some beefing up of known wear pionts at the the rear end. Some heavier ribs, skins, and a dual elevator trim actuator are included in the work.
This conversion appears to be operated at quite conservative limits. As for range (147 USG)we have flown Faro to our strip in Berkshire non- stop with two occupants.
Practical but expensive.