If you turn the crank slowly by hand and stop at the first sign of pistons hitting valves, you won't do any damage. There's a decent chance you can turn it all the way around without hitting them anyway, since it's not exactly a high-compression engine with lots of valve lift and big valves. If you're worried about it, pull the valve covers and loosen the rocker arms.

 

I maybe wrong but the rockers should be the rail torque type so its a simple job to remove the rockers.
However looking at the picture of the gears the chain teeth are worn to a point and its time for a new timing set .....

 

This one you don't need to worry about valves hitting pistons. Just line up the marks if they aren't already. Note the teeth on these timing gears appear much sharper than on older small block Chevys. What is the deflection on your chain - that is the way to check wear and stretch. Note mine in the photo has the optional timing chain tensioner that GM added in later years. My parts (including the tensioner were from Manley). What's up with the rusty crank snout on yours? You are aware there are timing marks for the balance shaft gear as well (the one behind the timing gear)?

 

Ok, She's all turned over and in alignment, thankfully i didnt have to pull off the Power steering pump and everything off the top of the motor to do so. problem now is that i grabbed the wrong one of two torque bars that was severely out of calibration, And sooner or later im ordering 3 new cam timing gear bolts as i dont trust the other two that didnt snap. Still, Thanks for the help folks.

As for the rusty crank end, Its been exposed to the Florida coastal air for the past 3 or so years, everything is fairly rusty and will be getting cleaned up before reassembly. The Chain itself is brand new and has barely any play in it. And yes i am aware of the Balance shaft timing marks, None of that has been removed since the motor was built by GM, and the gear teeth on the gears behind it are still in great condition so i'd wager thats all still in alignment though i'll check before buttoning it all up, How do they need to be aligned, Pointing at eachother?

 

it is, a nearly half inch thick layer of grease and grime and dirt. Its getting a pressure wash when its back together.

 

bring marks close to each other on both balance shaft gears and on timing gears.

 

Alright, Thanks. Will help a ton as im looking at removing the balance shaft now to get that bolt stem out. Is it normal for the balance shaft to be very stiff?

 

Don't understand "getting bolt stem out". Balance shaft should turn in it's bearings similarly to the camshaft with no lifters - but remember they are linked together by gears. IIRC the front bearing for the balance shaft is an actual roller bearing assembly that is pressed onto the front of the balance shaft behind a plate with two bolts.

 

In the end i managed to get it out without removing anything, just had to take a punch and a peen hammer to get the stem started, then out by hand. The balance shaft is much much stiffer then the cam, to the point of needing quite alot of leverage to rotate, Where in contrast the cam pretty much freewheels.

 

OK sounds like removing the remainder of a broken off bolt somewhere.

Better remove the balance shaft and find out why.