Valve job on os valves

Is that a $400 difference in valve job cost over a plain old "standard" valve job? As even that, won't be free.
The labor on the valve job I had done on the head on my latest slant was $425 total, and that was with a 70 thou mill, new exhaust seats, cutting seats for the oversized valves, finishing up my porting, a magnaflux to be sure we didn't oops and hit a water jacket, cut down tops of guides for positive seals and also for length so that I don't crash the retainers at full lift. Unsure if they had to put new guides in, don't remember any talk about that.
I supplied the valves (same ones you are talking about from Oregon cams) the positive seals and the 318 springs I had them install.
All total I have between $600-650 in this head. Parts included. Double what I spent on the last pair of 318 "302" casting heads with this same machine shop, that they got me all new valves for and they got me the positive type seals, they just did a regular standard valve job on those heads and only took 7 thou off the deck surface of (1/10 the amount I had them take off of this slant head)
I had the 318 heads done about a year and a half before they did the slant 6 head for me. But I figure that since the /6 is about 90-some CID less than what a 318 is, and my /6 is in a 1/2 ton truck, that this engine needed all the help it can get.
BTW the 318 is in a B body.