Try this place. I found it on another forum.

Antique Aero Engines
20 Curtiss Taxi
Santa Paula, CA 93060 - View Map
Phone: (805) 525-9464

I have no experience, but a quick internet search found this possible option.

https://www.airmarkoverhaul.com/

I would think you would know since you have two GO480s...

I find this site has quite a bit of helpful information since our Navion has more than a few things in common with the Beech.

http://csobeech.com/index.html

I heard from S-TEC the other day and only 6 PO's had been received at that time for the Navion 55x special pricing. If you plan to order, S-TEC closes down for the year on 21-December-2019...so that is really the last day.

If I remember right, there are two internal o-rings per cylinder and one o-ring to seal the cap. Three o-rings to re-seal each master cylinder. -MS28775-110 -MS28775-113 -MS28775-012 As another option, you can check with Plane Parts Inc, they have been offering o-ring kits for most of the Navion par...

I did mine a few years ago. They are standard o-ring part numbers. I should have the part numbers at the hangar. I will get them in the next few days.

The family plane...purchased new by my grandfather...great cross country cruiser for my family.

RIP

So my G model shows Vx as 98mph and Vy as 105mph. I think the canopy model has much lower speeds. Is this different due to the wing angle of incidence change or power or ?