i had an engine builder on the case and he couldnt find anywhere that could get them, even imported. i dont think its a popular mod in the usa to be honest ie using that engine and turbo charging it. i rang the usual manufacturers of steel rods ie farndon, arrow etc and they dont sell them off the shelf. i was told however they could be custom made if they had a standard rod to work off. i suspect most engine builders like jamsport and nms etc prob do get there rods from these companies but maybe the companies are contracted to only supply the rods through the chosen engine builder NOT the general public.
you could if you like ring around to nms etc asking if they could get you them just to buy, karl is very helpful and he may be able to help with the pistons too, the engine we have is 1860cc in standard form (82mm piston), when they do the conversion you have a choice of piston/bore size, 82.5mm, 82.75mm and 83mm ie 1905cc.
hope this helps, keep me updated mate.
dave.