Im not sure if this is true or not...but i have been told by several people that cylinder heads off a 360 engine will bolt right on to a 318 block. Like i said...im not sure if this is true or not..ive done some research and havent found anything positive yet...and i think its BS...but if you have any idea or not let me know, Thanks.

Magnum engine heads are the same.

360 heads of course would not work on a poly 318.

So 360 Magnum heads would fit onto a 318 Magnum block?

Yes.

would there be any real significant gains to putting 360 heads onto a 318 block or would it be a waste of my time?

Non Magnum 360 heads (340 heads also) will bolt directly onto any LA series ('67-'91) 318. It changes the tuning of the engine significantly. The intake and exhaust port size is much bigger in the 340/360 heads so the RPM for peak torque and hp moves up the RPM spectrum about 30%. Because of the change in tuning, it is easy to "over cam" the engine and end up with lousy performance. If you know what you are doing, you can make a serious performing engine out of an old 318.
The Magnum series usues the exact same head for both engines. That is why if you drive a 360 and then a 318, you will notice the the 318 has a lot less low rpm torque but comes on strong in the higher RPMs.

would there be any real significant gains to putting 360 heads onto a 318 block or would it be a waste of my time?
Well what do you think?

Taking heads from a 360 for your 318 would be just like taking heads from another 318. They are identical in every way.

Well what do you think?

Taking heads from a 360 for your 318 would be just like taking heads from another 318. They are identical in every way.

The engine would breath better

I used to have an old 305 chevy with 350 heads..it ran like a scalded ape
Physically the heads are the same (bolt pattern, size wise) but the valves are larger, thus it will be able to suck,squeese,bang,blow better

It will change the power/torque ratio somewhat