Swirl Port 308 302 info
The part you may be missing is the exh valves in the 360 heads you have came with a lower groove for the lock for use with the rotator. I've seen them both ways (stock height groove, and lower). My own truck has the lower groove ('87 360) and I'm running the smaller XE262 in it with no issues but a little extra preload on the exh springs (Comp 901s)
If you buy a set of stock 1.60 exh valves they will have the grooves in the rigth place now.