Another Advice Post

Hardened seats will up the cost another 90-120 depending on shop.

With a 1.88 in those heads, you are gonna be doing a lot of bowl and short turn work 'for one who doesn't do this professionally' to get them to flow as good as a bowl blended 1.78 valve.
As the turn gets steeper, the flow becomes less..and that's what that larger valve will do.

I'll be posting a thread to help you, read it.