The first time you do it, the paint marks or punch marks might be a good idea.

Confusion about 1/4 turn
 

One quarter of a turn is 90 degrees(4X90= 360). You seem to indicate that the bolt head is to be turned 90 degrees, but are turning it 180 degrees, or am I being obtuse here?

David, with most, if not all, head bolts have to be tightened in stages. In the M103, there is an initial torque, a second torque setting defined in an angle tighten of 90 deg and then a last tightening of 90 deg. The head bolts then have a conistant torque applied. Most engines today use the angle torque method.

Do not skip the middle step and thighten 180 deg.

I laid the head on the other day between rain storms. I torqued it down 10 ft/lbs just to seat the gasket and make sure no bugs crawled between it!. I finished torquing them down today but I pulled a few bolts first just check and make sure the light oil I gave them didn't puddle in the bottom of the holes (no problems there). I thought it was somewhat odd that center bolts were just "finger tight" when I came back to it today, and I definitely torqued them, though 10 lbs isn't much.
Anyway, It went fine, no other surprises. I did the white dots mentioned above and found it REALLY helpful, making the observation of completing the 90 degree turns very easy. Kinda hard to see the ones by the firewall though. A three foot breaker bar man-handled the bolts pretty well. I wouldn't say it was a workout, but I did break a sweat.
Thanks to all for the help, advice and comments.