I need to pull a head off my 360 to try and find out why the head gasket is leaking, it's leaking antifreeze in between #1 and #3 cylinders but luckily not in the oil. It's running down on the outside of the block, so my question is do the rockers have to adjusted for just pulling the head off or just put the head back on and torque to spec.

You should readjust. Nothing will go together the same. Gasket thickness may vary etc. Don't take anything for granted.
Are you sure that it is not the end header stud/bolt leaking and tracking back??? The end bolts are wet you know.

What about using a gasket that was on the motor with the other heads they was torqued down but the engine was never fired up, so should they be ok to reuse with the J heads. The one that is on the car and leaking is : Brand Fel-Pro
Manufacturer's Part Number Q1008
Part Type Head Gaskets
Product Line Fel-Pro Performance Head Gaskets
Summit Racing Part Number FEL-1008
UPC 084113010088

Bore (in) 4.180 in.
Bore (mm) 106.172mm
Gasket Material Steel core laminate
Compressed Thickness (in) 0.039 in.
Compressed Volume (cc) 8.900cc
Lock Wire No
Quantity Sold individually.
Notes Pre-flattened steel wire ring.
And the other one I took off is:Mr. Gasket Ultra-Seal Head Gaskets
Summit Racing Part Number MRG-5805G
UPC 084041023020

Bore (in) 4.140 in.
Bore (mm) 105.156mm
Gasket Material Steel core laminate
Compressed Thickness (in) 0.038 in.
Compressed Volume (cc) 8.382cc
Lock Wire No
Quantity Sold individually.,
So the one on the motor has a compressed thickness of 0.039 in and the one i want to reuse has 0.038 in and I'm not sure if this will cause a compression imbalance enough to hurt anything.

I wouldn't chance it. It isn't that big a job. Why is there never time to do a job right the first time but always time to do it over?

Well I thought the job was done right the first time the gasket and heads was put on by an engine builder who builds engines for show and hi-performance cars so I'm not sure why it's leaking. Not real sure at the moment it's a defect in the gasket, the studs leaking, or a cracked or warped head because he put the 2.02 valves in them but I didn't ask him to check them.

Just do the rocker adjustment. They stay in adjustment for so long, do it now and you won't have to worry about it for a long time.

I tried what you're thinking once, thought "oh ya, I didn't touch the exhaust rockers or valves, just played with the intakes so I can just bolt my rockers back on and only adjust the intake rockers not the exhaust rockers." Want to know what happened? Some of the exhaust rockers were far enough out of spec now that two of the exhaust valves didn't close all the way, resulting in zero compression on those cylinders! I didn't make any other changes and this was on a 4cyl engine with an overhead cam with manual lash adjusters. No lifters or pushrods even!