I'm planning my winter project early and I wanted to do some research.
I wanted to switch my 906 heads to a set of 516's I've got. I planned on putting in new stainless valves, increasing the exhaust to 1.74, new springs and gasket matching the ports. Do I need to do anything else? Bronze guides? or just knurl the originals? what about hardened seats?
I also planned on surfacing the heads just to make them true.
I have trw low compression pistons and I thought I might see a nice gain in power by doing this.
Any reason why I should not do this?

thanks for the input
scott