Rich,
I just did a search for "davits" and came up with 24 hits. You might want to look there first. The search function is in the blue bar near the top of the page. Hope this helps.

I have no first hand experience - just saw them at the Chicago Strictly Sail show and WOW! Very robust 1 1/8 SS tubing, very nice blocks; and all the needed parts including mounts, cross rails, and line handling cleats are included at about $1200. Rep said they could make any rise or reach (within reason) we need.

I elected to get Garhauer davits and they made them to custom sizes for just a nominal extra charge over the standard. I am very happy with them, but make sure you decide exactly how you plan to install them relative to the lifting points on your dink.

The upper blocks do not swivel athwartships, so your lifting points need to be pretty much directly under the davit blocks. Otherwise, as you lift, you are trying to pull the line off the sheaves and that adds a lot of extra friction and in the worst case the opportunity to foul the line big time. This is a consideration if you ever change dinghies and find the lifting points differ significantly.

I am not sure of any davit manufacturer that has such a swiveling block except for the Ocean Marine Systems.

Closer to home maybe call Stainless Outfitters in Barrie. They do custom fabricating for about the same money as anyone else charges for their stock designs. They built our davits and wind gen/outboard motor lift and they do very nice work.

Yes, it will lower the stern. We have a 9' RIB with a 9.9 Tohatsu and a 220 watt solar panel on the davits and all that weight definitely makes the waterline disappear.

That squat in the stern when you're motoring or sailing though is normal and has nothing to do with weight back there, our boat did that with nothing on the stern at all and it doesn't squat any worse when moving with all that stuff there now.