Thinking about buying a 20x60 go devil hull for my 35hp gtr. What kind of speeds should I expect out of this? Will it porpoise with just me driving?

26 or so.
Nope.

North la Hunter has run a 2048 with a stock 35. He may can provide more answers if you have additional questions. A 2060 will run similar to a 2048.

I run a 37 GD on an 1860 GD boat. I wouldn't hesitate to run it on 2' more hull. You won't be he fastest but it will work just fine. I can't speak to the frame specifics with that hull but plenty others have done it and had good results.

Okay good deal. Thats what I was hoping.

My buddy has a 2060 GD hull with a 37 GDSD I have the same motor on the 1860 and my rig is definitely faster but not by that much. I run right around 30 mph empty and I would say he runs 27 bumping 28. I will say those boats will definitely tote a load and still get on step the 60 inch bottom will also take up some real estate in some hard turns.

Ive got a 37 Gtr to on a 18x60 go devil and I wouldn't have to think twice about putting it on a 20ft hull. It carries a load great as it is but that extra 2ft of floor would be real nice for pileing in decoys and gear with plenty of room

I had a 35 GD on a 20x 72 aluminum skiff built by Weegee Company in Jefferson Parish in 2011, and I'd get around 26 mph . Hope that's gives you a good idea.

Could you guys that have the 20x60 godevils with GTR's post a picture of how you bolted to the transom. I'm worried if I'm not perfectly center that I will catch the edge of one of those transom braces and make a mess.
In between those braces on the inside measures exactly 8". Measuring from the back of the transom from the inside of each bolt is 8 3/8". I'm not even sure if that enough space to catch both braces and if it is the washer will probably be hanging over.
I will try to take a picture of what I have going on when I get home because I probably didn't explain this very well.

You cant make the bolts catch both braces, the spaceing just isnt right anyway you do it. With that being said most likely you wont want your motor dead center anyways, that produces alot of tiller torque. I had mine dead center and it was all my skinny ass had to keep it from pushing me out. Its now mounted several inches off center to the port side with no tiller torque and still runs just as good. I have one bolt in the port side brace and the other is just through the transom and i ran a piece of flat bar between the braces and bolted it to the flat bar and just tightened it up like that.