Norm, I have never really had to much trouble with the Victa Powertorque engine. It was actually the first engine I started repairing a few years ago. Generally in about 1.5 hours I can fully service and fix any faults on a powertorque and ensure it is ready for a new home. Rarely if ever to I get any complaints about their reliability. They are my favourite engine to refurbish and repair due to their simplicity. They are also a cost effective engine to service. Many cut corners with servicing however that�s not something I promote.
There is a few peculiarities with the carbs that I have worked out but things like over reving and easy starting are pretty simple to get right.
I have narrowed down a couple of good cost effective suppliers for parts and don�t have too many issues with them.
I�d be happy to share a few things I have learnt over the last few years via a call if you would like. It would take too long to write them all done.
Note: I am still learning stuff everyday!
Regarding your query on bottom seals � these are protected by the flywheel and rarely are the cause of over revving in my opinion. Others may think differently.
As for swapping carbs its not really needed if you get a right replacement parts.