Personally I would not run the engine without a prop. Additionally you need to do the crank test to make sure that the crank was not bent. If the engine was not running the easy thing to do is check the runout on the prop flange. Refer to the mantelpiece manual. All that you will need is a dial indicator which is available from Harbor Freight. My guess is that you will find that it is ok but if not the engine will destroy its self. Also I would pull the gearbox and do the runout on the end of the crank just to be safe.
My cabine did have the cross member, I suggest adding a king post at the center of the crossmember going to the low point of the cabine to help strengthen the cabine. Maybe attaching the cabine to the truss would help, but I just don't know. I do know that part of the failure mode is the cross member is deflected downward as the sides of a he fuselage are pulled inward maybe the problem is that the fuselage just isn't stout enough for this style of gear. my new gear has Roberts Rage struts, the cabine also has X bracing in addition to the cross member. The front mount was built heavier with additional holes to mount the cabine. The downside is that it is not a simple bolt on application and requires new mount fabrication. I also built the gear legs wider to attach to the rear gear mount at the strut attach point. I see that Kitfox has also went to a wide stance on their gear legs. The center attach point for the standard gear is a weak point. One thing that I would change is the angle of the gear legs are to steep as are the gear legs on the so called Bush Gear design. If you think of that gear as a Sunday flier gear not as a Backcountry airstrip gear it is probably very serviceable for the average pilot. I do know that I was not descending at anywhere near500 feet per minute when the gear/fuselage failure happened Jim i also reinforced the seat truss on the first rebuild and that has worked good. Here is a link to photo of what my gear looks like now.
The math looks pretty good and I am sure that the engineering on the Tacoma Narrows Bridge looked good also. After two failures I can attest that there are flaws in the design of this style of gear but if you grease it on every time they will last you a life time. If mine were the only failures my experience could be discounted but ther have been others. The wider stance does make the plane handle much better. I sure can agree the doing business with Highwing LLC was right on the money and I would do business with them again but not to purchase that gear.
A split bushing can easily be made and installed using the method Doug showed with his one piece bushing. This need not be a deal breaker just some of a build's little challenges along the way. Take a deep breath, you only need to solve one issue at a time. It is worrying to find these kinds of issues and you will probably do well to have another builder help you go thru the plane to see what other problems are lurking. where are you located? Maybe some one is close by and could have a look at it with you.
One caution about pulling the plane facing forward that I am sure Bandit addressed, be sure to plug the end of the spars and the wing without tanks to avoid pressuring up the under cambered wing and pulling the fabric loose especially if the wing is not rib stitched...
As mentioned in my post in another thread I used one small hard rivet thru the aluminum forward of the break area. I also clad all of the tails when I fixed the broken one. Not sure if the rivet was necessary but I have not had anymore problems and would use the rivet again if I built another plane.