rod bearings in my 400/512 at the moment are clevite CB 743H and have a chamfer on one side. i have just received new clevite CB743HND with no chamfer but they are more narrow so looks like no need to chamfer is this right. TIA

look closer, they do still have a very small chamfer on them and there is an upper and lower bearing.

yes there is a very small chamfer if you look hard do you think they will be ok, i think the n in the p/n is for narrow bearing for aftermarket large fillet cranks

yes, the N stands for narrow. it's important to make sure you put the upper half in the upper half of the rod and vice-versa. failure to do that WILL result in engine damage.
those bearing are clearly marked.
do i think they will be okay? can't say since i'm not the guy doing the assembly but it "should" be.

Those bearings will be fine , used the 'N' series in a megablock spraying 400hp , these don't have the white metal right? , they look pretty rough out the box , like they've been heated with a torch.

Right,

The older, regular width is about 0.890" wide and the "N" narrow bearing is about 0.838" wide. And they are marked upper and lower on the back. The "HN" are what Clevite has to offer instead of the older "H"

yes they do look a bit rough out of the box, is there any prep work apart from clean and assembley lube?,also cant get them round the wrong way as there is a dowel hole in lower for ali rods. so the narrow bearing saves having to chamfer, should be good to go right. thanks again