Chain tension and tensioning a chain

it is unlikely that the cranks are bent, but if they are it should be easy to see.
If you spin them they should wobble.

I havent seen the Sheldon menthod of chainring fitting. But Id just say use common sense, leave the bolts half tight and give it a few spins with a snug chain on, it should centre itself, then tighten up at opposite corners.

You should even have to do this if you have a modern/decent pair of cranks, as the chainrings fit very accurateley anyway.

Too right man, I've done all these things multiple times! But I can't see anything obvious... I don't want to cunt 150 on Suginos and a ring if it isn't going to remedy anything.

Edit, Sheldon method is as you stated.