Hi Tadawson. I find if I double click on the images April 28, the resulting images are extremely clear. So, I doubt that I can do any better. Can you reference for me on my photos where the "throttle plate/linkage" is so that I can try your suggestion?To the OP, I think I asked this earlier, but the response may have been lost . . . Have you checked the gov linkage setup IE the positiom of the gov arm on the shaft coming out of the block? That can also easy result in an overrev situation. I also forget (sorry!), but does the throttle control have any effect on speed at all? IE, can you reduce it to idle, but it overrevs when you bring the contol up, or?? Also, if you push the throttle plate/linkage closed by hand, can you reduce speed? If so, I doubt a carb replacement will do much, but if you cannot, then it may well help.
Also, note the metal rod with the "U" shaped bend in Ziggy's second photo. This is the speed adjustment point on these engines. After setting the gov link, you bend this open or closed to set the top governed speed.
I can't see anything that stands out as wrong on your linkages from your photos, but they are showing up verry blurry here, so it is really hard to be certain. Any chance you can attach some higher res images?