10.5-11.5 hours, depending on which flat rate manual they are using.
As for gaskets, I prefer OEM, Victor or Fel-pro.
Be aware that the head bolts are recommended to be replaced when replacing the head gaskets.
This kit from Northern Auto Parts
(HST9957PT2 $202.91) contains All of the upper end gaskets, except exhaust gaskets.
You will need this head bolt set (Head Bolt Set VICTOR GS33377 $29.64) or equivelant.