I am new to this site and I have a question about swapping a Chevy motor with a Pontiac one. Please help!

I have a 68 Chevelle that I am restoring and it had a 77 or 78 305 in it when I got the car. I want to put a 350 into it, and after looking around I found a complete 69 Pontiac Tempest LeMans S that has a stock 350 in it. The body has alot of rust and is pretty far gone. Being that it is a GM product, how hard or easy will it be to bolt up to my fresh rebuilt Turbo 350 to this engine? I have read somewhere that Buick, Olds, and Pontiac transmissions are interchangable (B.O.P) and the pictures that I have found, the only difference is the "valley" in the top of the Pontiac trans.  

I have not attempted this particular swap, but I had a 76 chevy 4X4 with the exact engine in it. The motor mounts on a ponti engine are a couple of inches further forward than a chevy block, I do not know of a swap kit. There are adapter plates for bolting a chevy bellhousing to the pontiac tranny. Another problem is the starter is on the drive side and your batt tray is on the pass. So use larger size batt cables b/c of the extra length. If, its worth the trouble, Pontiacs are much heavier and more expensive to modify. Besides a SBC will be much more valuble in your chevelle.