they both have pros and cons

318 head..
small valves with small port/runners
makes better lowend torque off idle,gives up topend flow/rpm,gains a comp bump with closed chambers.

360 heads..
bigger valves with bigger ports/runners
gives up lowend torque,gains topend flow/rpm,drops comp ratio with large open chambers.

remember,only early magnum blocks will be drilled to oil thru the head to shaft mount rockers LA style.

watch the cam also,not all roller cams are drilled for LA style oiling.

whats the plan on how to oil the rockers on your build?