The broken blade in the reel obviously must be replaced and this is not a simple job. The sprockets are badly worn, which is usually a result of the chains having worn out first, nearly always due to failure to keep them clean and lubricated. It is evident that you have some money to spend. However to make a proper assessment of the condition of the machine you need to examine and photograph the frame rails and dismantle and inspect the engine shaft clutch. There are several threads on Outdoorking dealing with these matters.
I see that your clutch is of the later type with set screws rather than a captive cotter pin, and this probably means it is less likely to have come loose at some time and aggravated the characteristic vibration of the frame rails which causes them to crack. As a preliminary comment, aside from the broken blade and the worn-out chains and sprockets, the situation looks fairly promising to me. However what we need is comment from SB45 experts such as bonnar_bloke and Deejay.
