Cylinder Heads hard to install have 1989 chevy small block 350 engine ?

somewhat

Nah. Very easy if you are familiar with the job.

No not really. You will need a torque wrench that has a range up to 70 ft lbs atleast though.

When you torque the heads down you have to follow the right order. The order can be found here http://www.small-block-chevy.com/assemblyspec.html

That page gives the right order but myself I torque them in 3 steps rather than 2 like they list

30, 45, 65 ft lbs

Other than that it’s real simply.

Clean block deck with brake parts cleaner and a rag, scrap off any old gasket. Feel with heads if decks are smooth, if not use a green Scotch Brite pad to smooth it up.

Lay gaskets on decks (noting which way is up on gasket)

Sit heads over on the block (decks has 2 dowl pins) to help you line up heads.

put thread sealer (teflon paste or other type of sealer) on the threads of the bottom row of bolts (they go into the water jackets)

Put alittle oil or moly grease under the heads of all the bolts.

Pay attion to the bolts as theres 3 lenghts of bolts. (shortest on outside bottom row, next to shortest 1 on each end in a gully, and longest in all other spots)

slid bolts in and torque down

Then put your pushrods, rockers, etc on. Intake on and adjust the valves, stab dizzy in on compression stroke TDC for #1 cyl,