1972 Combat Interstate Camshaft

Hello I am currently stripping down the engine on my 1972 Combat Interstate, which I have owned from new, to investigate the cause of low oil pressure when hot. The bottom end has never been apart before, so when I split the crankcases yesterday, I was surprised to find that a standard cam was fitted rather than a 2S. All this time, I’ve never understood descriptions of the power characteristics of the 2S cam, and now I know why! The engine is number 2083**, and the ID plate shows a build date of September 72.  The cylinder head and the carburettors are standard Combat. Anyway, the cam runs in the 72 standard scrolled bushes, with the thrust washers both sides of the timing side bush, but they both lack the fragile tags, which reportedly get broken off, but I cannot see any indication of a breakage. The thrust washers have clearly been spinning against the cases for some time. Being a standard cam, it is scrolled, so it would appear that I can replace the timing side bush and the 2 flat thrust washers with either the 73 850 06.3020 bush, or 2 Mk3 06.5428 bushes. Does anyone have experience of which is the better option in making this replacement, and any problems that may be encountered. Will the spacing be correct? I do not have any machining facilities.

Thanks for your help.

Ray