3 hours? I assume you aren't getting the heads milled? You must like to do this job again.
I could honestly do it in a day if I started early at like 7:00 am, dropped the heads off at like 11:30 and then got them back that day, put it all back together, I'd be driving it around 5:00 pm. Thats if you don't change anything else other than the gaskets.
On mine I changed, plugs, wires, hoses, belts, tensioners, painted valve covers, painted brackets, painted pulleys, ported heads, cut off cats, changed cam and crank sensors, IAC and tps, and coolant temp sensor, t-stat, temp switch, did the fan mod, tb coolant bypass, new PCV valve, cleaned and painted blower, changed fluid, flushed radiator and block, etc...
I could do it over a weekend and I'd charge $500.00 for my time/labor w/ supplied gasket set and head bolts plus you pay for machine work.
Look at my member page 2 for engine pics of my painted blower setup.